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Medical Glossary

H

  • H. pylori
  • A type of bacterium that causes inflammation and ulcers in the stomach or small intestine. People with H. pylori infections may be more likely to develop cancer in the stomach, including MALT (mucosa-associated lymphoid tissue) lymphoma. Also called Helicobacter pylori.
  • hA20
  • A monoclonal antibody that is being studied in the treatment of refractory B-cell non-Hodgkin lymphoma. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. hA20 binds to the protein CD20, which is found on B cells (a type of immune system cell), and some types of lymphoma cells. Also called HCD20, IMMU-106, and veltuzumab.
  • HAART
  • Treatment for human immunodeficiency virus (HIV) infection that uses a combination of several antiretroviral drugs. The drugs inhibit the ability of the virus to multiply in the body, and they slow down the development of AIDS. Also called highly active antiretroviral therapy.
  • hair follicle
  • A shaft or opening on the surface of the skin through which hair grows.
  • hairy cell leukemia
  • A rare type of leukemia in which abnormal B-lymphocytes (a type of white blood cell) are present in the bone marrow, spleen, and peripheral blood. When viewed under a microscope, these cells appear to be covered with tiny hair-like projections.
  • Haldol
  • A drug used to treat certain mental and neurological disorders. It is also being studied in the treatment of nausea and vomiting caused by some cancer treatments. It is a type of antiemetic and a type of antipsychotic. Also called haloperidol.
  • half-sibling
  • A person’s brother or sister who has one parent in common.
  • hallucination
  • A sight, sound, smell, taste, or touch that a person believes to be real but is not real. Hallucinations can be caused by nervous system disease, certain drugs, or mental disorders.
  • halofuginone hydrobromide
  • A substance that is being studied for its ability to slow the growth of connective tissue and to prevent the growth of new blood vessels that tumors need to grow. It is a type of quinazolinone alkaloid and a type of antiangiogenesis agent.
  • haloperidol
  • A drug used to treat certain mental and neurological disorders. It is also being studied in the treatment of nausea and vomiting caused by some cancer treatments. It is a type of antiemetic and a type of antipsychotic. Also called Haldol.
  • Halsted radical mastectomy
  • Surgery for breast cancer in which the breast, chest muscles, and all of the lymph nodes under the arm are removed. For many years, this was the breast cancer operation used most often, but it is used rarely now. Doctors consider radical mastectomy only when the tumor has spread to the chest muscles. Also called radical mastectomy.
  • hamartoma
  • A benign (not cancer) growth made up of an abnormal mixture of cells and tissues normally found in the area of the body where the growth occurs.
  • hand-foot syndrome
  • A condition marked by pain, swelling, numbness, tingling, or redness of the hands or feet. It sometimes occurs as a side effect of certain anticancer drugs. Also called palmar-plantar erythrodysesthesia.
  • haplotype
  • A set of closely linked genetic markers present on one chromosome which tend to be inherited together.
  • happy major
  • A plant whose seeds and root have been used in some cultures to treat certain medical problems. It may have antioxidant effects. The scientific name is Arctium lappa . Also called burdock and lappa.
  • hard palate
  • The front, bony part of the roof of the mouth.
  • hawthorn fruit
  • The fruit of the hawthorn tree or bush. It has been used in some cultures to treat certain medical problems, including heart problems and gastrointestinal problems.
  • hazard ratio
  • A measure of how often a particular event happens in one group compared to how often it happens in another group, over time. In cancer research, hazard ratios are often used in clinical trials to measure survival at any point in time in a group of patients who have been given a specific treatment compared to a control group given another treatment or a placebo. A hazard ratio of one means that there is no difference in survival between the two groups. A hazard ratio of greater than one or less than one means that survival was better in one of the groups.
  • HCA
  • A chemical that is formed when meat, poultry, or fish is cooked at high temperatures, such as frying, broiling, and barbecuing. HCAs are carcinogens (substances that may cause cancer). Also called heterocyclic amine.
  • HCD20
  • A monoclonal antibody that is being studied in the treatment of refractory B-cell non-Hodgkin lymphoma. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. HCD20 binds to the protein CD20, which is found on B cells (a type of immune system cell), and some types of lymphoma cells. Also called hA20, IMMU-106, and veltuzumab.
  • HCP
  • Healthcare proxy. A type of advance directive that gives a person (such as a relative, lawyer, or friend) the authority to make healthcare decisions for another person. It becomes active when that person loses the ability to make decisions for himself or herself. Also called healthcare proxy.
  • hCRF
  • A substance being studied in the treatment of brain cancer. It is made naturally by the hypothalamus (a part of the brain) and can also be made in the laboratory. hCRF may help reduce symptoms caused by edema (swelling) of the brain. It is a type of neurohormone. Also called human corticotropin-releasing factor.
  • HDAC inhibitor
  • An enzyme that removes a small molecule called an acetyl group from histones (proteins found in chromosomes). This changes the way the histones bind to DNA and may affect its activity. HDAC inhibitors are being studied in the treatment of cancer. Also called histone deacetylase.
  • HDAC inhibitor SNDX-275
  • A substance being studied in the treatment of several types of cancer. It blocks enzymes needed for cell division and may kill cancer cells. It is a type of histone deacetylase (HDAC) inhibitor. Also called entinostat and SNDX-275.
  • HDR
  • An amount of radiation that is greater than that given in typical radiation therapy. HDR is precisely directed at the tumor to avoid damaging healthy tissue, and may kill more cancer cells in fewer treatments. Also called high-dose radiation.
  • head and neck cancer
  • Cancer that arises in the head or neck region (in the nasal cavity, sinuses, lips, mouth, salivary glands, throat, or larynx [voice box]).
  • healing touch
  • A form of complementary and alternative medicine based on the belief that a vital energy flows through the human body. This energy is said to be balanced or made stronger by practitioners who pass their hands over a patient's body. Healing touch is being studied in patients receiving cancer treatments to find out if it can improve quality of life, boost the immune system, or reduce side effects Also called therapeutic touch.
  • Health Insurance Portability and Accountability Act
  • A 1996 U.S. law that allows workers and their families to keep their health insurance when they change or lose their jobs. The law also includes standards for setting up secure electronic health records and to protect the privacy of a person’s health information and to keep it from being misused. Also called HIPAA and Kassebaum Kennedy Act.
  • healthcare provider
  • A licensed person or organization that provides healthcare services.
  • healthcare proxy
  • A type of advance directive that gives a person (such as a relative, lawyer, or friend) the authority to make healthcare decisions for another person. It becomes active when that person loses the ability to make decisions for himself or herself. Also called HCP.
  • healthy control
  • In a clinical study, a person who does not have the disorder or disease being studied. Results from healthy controls are compared to results from the group being studied.
  • heart cancer
  • A rare cancer that develops in tissues of the heart. Also called cardiac sarcoma.
  • heat-shock protein
  • One of a group of proteins that help protect cells from stresses such as heat, cold, and low amounts of oxygen or glucose (sugar). Heat-shock proteins help other proteins function in normal cells and may be present at high levels in cancer cells. Blocking the activity of a heat-shock protein called HSP90 is being studied in the treatment of cancer. Other heat-shock proteins including HSP70 and gp96 are being studied in vaccines to treat cancer. Also called HSP and stress protein.
  • Hedyotis diffusa
  • An herb used in traditional Chinese medicine to treat certain medical problems. It has been used to boost the immune system and may have anticancer effects.
  • helical computed tomography
  • A detailed picture of areas inside the body. The pictures are created by a computer linked to an x-ray machine that scans the body in a spiral path. Also called spiral CT scan.
  • helical tomotherapy
  • A type of therapy in which radiation is aimed at a tumor from many different directions. The patient lays on a table and is moved through a donut-shaped machine. The radiation source in the machine rotates around the patient in a spiral pattern. Before radiation, a 3-dimensional (3-D) image of the tumor is taken. This helps doctors find the highest dose of radiation that can be used to kill tumor cells while causing less damage to nearby tissue. Helical tomotherapy is a type of intensity-modulated radiation therapy (IMRT). Also called tomotherapy.
  • Helicobacter pylori
  • A type of bacterium that causes inflammation and ulcers in the stomach or small intestine. People with Helicobacter pylori infections may be more likely to develop cancer in the stomach, including MALT (mucosa-associated lymphoid tissue) lymphoma. Also called H. pylori.
  • helper T cell
  • A type of immune cell that stimulates killer T cells, macrophages, and B cells to make immune responses. A helper T cell is a type of white blood cell and a type of lymphocyte. Also called CD4-positive T lymphocyte.
  • hemagglutinin-neuraminidase
  • A protein found in the outer coat of paramyxoviruses. This protein helps virus particles bind to cells, making infection easier.
  • hemangiopericytoma
  • A type of cancer involving blood vessels and soft tissue.
  • hemangiosarcoma
  • A type of cancer that begins in the cells that line blood vessels.
  • hematogenous
  • Originating in the blood or spread through the bloodstream.
  • hematologic cancer
  • A cancer of the blood or bone marrow, such as leukemia or lymphoma.
  • hematologist
  • A doctor who specializes in treating blood disorders.
  • hematoma
  • A pool of clotted or partially clotted blood in an organ, tissue, or body space, usually caused by a broken blood vessel.
  • hematopoiesis
  • The formation of new blood cells.
  • hematopoietic growth factor
  • A group of proteins that causes blood cells to grow and mature.
  • hematopoietic tissue
  • Tissue in which new blood cells are formed.
  • hematoporphyrin derivative
  • A drug used in photodynamic therapy that is absorbed by tumor cells. When exposed to light, it becomes active and kills the cancer cells.
  • hematuria
  • Blood in the urine.
  • heme
  • The part of certain molecules that contains iron. The heme part of hemoglobin is the substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.
  • hemihypertrophy
  • A condition in which one side of the body or a part of one side is larger than the other. Children with hemihypertrophy have an increased risk of developing certain types of cancer, including Wilms tumor (a childhood kidney cancer) and liver cancer.
  • hemilaryngectomy
  • An operation to remove one side of the larynx (voicebox).
  • hemochromatosis
  • A condition in which the body takes up and stores more iron than it needs. The extra iron is stored in the liver, heart, and pancreas, which may cause liver disease, heart problems, organ failure, and cancer. It may also cause bronze skin, diabetes, pain in the joints and abdomen, tiredness, and impotence. Hemochromatosis may be inherited, or it may be caused by blood transfusions. Also called iron overload.
  • hemoglobin
  • The substance inside red blood cells that binds to oxygen in the lungs and carries it to the tissues.
  • hemophagocytic lymphohistiocytosis
  • A rare disorder in which histiocytes and lymphocytes (types of white blood cells) build up in organs including the skin, spleen, and liver, and destroy other blood cells. Hemophagocytic lymphohistiocytosis may be inherited or caused by certain conditions or diseases, including infections, immunodeficiency (inability of the body to fight infections), and cancer. Also called HLH.
  • hemophilia
  • Group of hereditary disorders in which affected individuals fail to make enough of certain proteins needed to form blood clots.
  • hemoptysis
  • Coughing or spitting up blood from the respiratory tract.
  • hemorrhage
  • In medicine, loss of blood from damaged blood vessels. A hemorrhage may be internal or external, and usually involves a lot of bleeding in a short time.
  • hemorrhoid
  • An enlarged or swollen blood vessel, usually located near the anus or the rectum.
  • heparin
  • A substance that slows the formation of blood clots. Heparin is made by the liver, lungs, and other tissues in the body and can also made in the laboratory. Heparin may be injected into muscle or blood to prevent or break up blood clots. It is a type of anticoagulant.
  • hepatectomy
  • Surgery to remove all or part of the liver.
  • hepatic arterial infusion
  • Refers to the liver.
  • hepatic arterial occlusion
  • A block in blood flow to the liver. It can happen while giving chemotherapy through a catheter in the hepatic artery. Sometimes doctors use drugs or other agents to cause hepatic arterial occlusion on purpose. This block of blood flow to the liver helps kill cancer cells growing in the liver.
  • hepatic artery
  • The major blood vessel that carries blood to the liver.
  • hepatic portal vein
  • A blood vessel that carries blood to the liver from the stomach, small and large intestines, spleen, pancreas, and gallbladder. Also called portal vein.
  • hepatic veno-occlusive disease
  • A condition in which some of the veins in the liver are blocked. It is sometimes a complication of high-dose chemotherapy given before a bone marrow transplant and is marked by increases in weight, liver size, and blood levels of bilirubin.
  • hepatitis A vaccine
  • Disease of the liver causing inflammation. Symptoms include an enlarged liver, fever, nausea, vomiting, abdominal pain, and dark urine.
  • hepatitis A virus
  • A virus that causes a serious liver disease. It is usually spread by contact with an infected person’s stool by eating food he or she has handled after not washing hands, but it can be spread in other ways. Symptoms of infection include jaundice, dark urine, and fever and other flu-like symptoms.
  • hepatitis B virus
  • A virus that causes hepatitis (inflammation of the liver). It is carried and passed to others through blood or sexual contact. Also, infants born to infected mothers may become infected with the virus.
  • hepatitis C virus
  • A virus that causes hepatitis (inflammation of the liver). It is carried and passed to others through blood or sexual contact. Also, infants born to infected mothers may become infected with the virus.
  • hepatitis D virus
  • A type of hepatitis virus that may be present in the body at the same time as the hepatitis B virus. It makes the hepatitis (inflammation of the liver) caused by hepatitis B much worse. The hepatitis D virus and the hepatitis B virus are spread to others through blood or sexual contact. Infants born to infected mothers may also become infected with the virus. Also called hepatitis delta virus.
  • hepatitis delta virus
  • A type of hepatitis virus that may be present in the body at the same time as the hepatitis B virus. It makes the hepatitis (inflammation of the liver) caused by hepatitis B much worse. The hepatitis delta virus and the hepatitis B virus are spread to others through blood or sexual contact. Infants born to infected mothers may also become infected with the virus. Also called hepatitis D virus.
  • hepatitis E virus
  • A virus that causes hepatitis (inflammation of the liver). It is usually spread through food that has been handled by an infected person, or through drinking water that is contaminated with human waste.
  • hepatitis G virus
  • A virus that may be found in patients with hepatitis (inflammation of the liver). It is spread to others through blood or sexual contact. Infants born to infected mothers may also become infected with the virus.
  • hepatobiliary
  • Having to do with the liver, bile ducts, and/or gallbladder.
  • hepatoblastoma
  • A type of liver tumor that occurs in infants and children.
  • hepatocellular carcinoma
  • A type of adenocarcinoma, the most common type of liver tumor.
  • hepatocyte
  • A liver cell.
  • hepatoma
  • A liver tumor.
  • hepatomegaly
  • Enlarged liver.
  • HER1
  • The protein found on the surface of some cells and to which epidermal growth factor binds, causing the cells to divide. It is found at abnormally high levels on the surface of many types of cancer cells, so these cells may divide excessively in the presence of epidermal growth factor. Also called EGFR, epidermal growth factor receptor, and ErbB1.
  • HER2/neu
  • A protein involved in normal cell growth. It is found on some types of cancer cells, including breast and ovarian. Cancer cells removed from the body may be tested for the presence of HER2/neu to help decide the best type of treatment. HER2/neu is a type of receptor tyrosine kinase. Also called c-erbB-2, human EGF receptor 2, and human epidermal growth factor receptor 2.
  • herba Scutellaria barbatae
  • An herb used in traditional Chinese medicine to treat certain medical problems. It may have anticancer effects.
  • herbal medicine
  • Having to do with plants.
  • herbal supplement
  • A product made from a plant that is thought to be useful in treating disease or staying healthy. Herbal supplements are taken by mouth.
  • herbicide
  • A chemical that kills plants.
  • Herceptin
  • A monoclonal antibody that binds to HER2 (human epidermal growth factor receptor 2), and can kill HER2-positive cancer cells. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. Herceptin is used to treat breast cancer that is HER2-positive and has spread after treatment with other drugs. It is also used with other anticancer drugs to treat HER2-positive breast cancer after surgery. Herceptin is also being studied in the treatment of other types of cancer. Also called trastuzumab.
  • hereditary leiomyomatosis and renal cell cancer syndrome
  • Transmitted from parent to child by information contained in the genes.
  • hereditary mutation
  • A gene change in a body's reproductive cell (egg or sperm) that becomes incorporated into the DNA of every cell in the body of the offspring. Hereditary mutations are passed on from parents to offspring. Also called germline mutation.
  • hereditary nonpolyposis colon cancer
  • An inherited disorder in which affected individuals have a higher-than-normal chance of developing colorectal cancer and certain other types of cancer, often before the age of 50. Also called HNPCC and Lynch syndrome.
  • heritage
  • Something handed down from the past, such as a tradition, birthright, or inherited traits.
  • hernia
  • The bulging of an internal organ through a weak area or tear in the muscle or other tissue that holds it in place. Most hernias occur in the abdomen.
  • heroin
  • A substance made from morphine. Heroin is very addictive and it is illegal to use or sell it in the United States. It is a type of opiate.
  • herpes simplex virus
  • A type of virus that causes herpes infections and has DNA as its genetic material. There are two types of herpes simplex viruses. Infections with type 1 viruses cause cold sores on the lips or nostrils. Infections with type 2 viruses cause sores on the genitals (external and internal sex organs and glands). Also called HHV, HSV, and human herpesvirus.
  • herpesvirus
  • A member of the herpes family of viruses.
  • heterocyclic amine
  • A chemical that is formed when meat, poultry, or fish is cooked at high temperatures, such as frying, broiling, and barbecuing. Heterocyclic amines are carcinogens (substances that may cause cancer). Also called HCA.
  • heterogeneous
  • Made up of elements or ingredients that are not alike.
  • heterogenic
  • Derived from a different source or species. Also called heterogenous.
  • heterogenous
  • Derived from a different source or species. Also called heterogenic.
  • heterozygous genotype
  • Occurs when the two alleles at a particular gene locus are different. A heterozygous genotype may include one normal allele and one mutation, or two different mutations. The latter is called a compound heterozygote.
  • hexyl 5-aminolevulinate
  • A substance that is used to find and kill tumor cells. It enters tumor cells and becomes activated when exposed to a special type of light. A chemical reaction causes the cells to produce fluorescent light and die.
  • HGS-ETR1
  • A substance being studied in the treatment of some types of cancer. It binds to a protein called TRAIL R1 on the surface of some tumor cells. This may kill the tumor cells. HGS-ETR1 is a type of monoclonal antibody. Also called anti-TRAIL R1-mAb and mapatumumab.
  • HGS-ETR2
  • A substance being studied in the treatment of some types of cancer. It binds to a protein called TRAIL-R2 on the surface of some tumor cells, which may kill the tumor cells. HGS-ETR2 is a type of monoclonal antibody. Also called anti-TRAIL R2 mAb HGS-ETR2 and lexatumumab.
  • HHV8
  • A type of virus that causes herpes infections and has DNA as its genetic material. There are two types of HHVs. Infections with type 1 viruses cause cold sores on the lips or nostrils. Infections with type 2 viruses cause sores on the genitals (external and internal sex organs and glands). Also called herpes simplex virus, HSV, and human herpesvirus.
  • HIFU
  • A procedure in which high-energy sound waves are aimed directly at an area of abnormal cells or tissue in the body. The waves create heat that kills the cells. HIFU is being studied in the treatment of prostate cancer and some other types of cancer and other diseases. Also called high-intensity focused ultrasound therapy.
  • high blood pressure
  • A blood pressure of 140/90 or higher. High blood pressure usually has no symptoms. It can harm the arteries and cause an increase in the risk of stroke, heart attack, kidney failure, and blindness. Also called hypertension.
  • high blood sugar
  • Higher than normal amount of glucose (a type of sugar) in the blood. High blood sugar can be a sign of diabetes or other conditions. Also called hyperglycemia.
  • high grade
  • A term used to describe cells that look abnormal under a microscope. These cells are more likely to grow and spread quickly than cells in low-grade cancer or in growths that may become cancer.
  • high-dose chemotherapy
  • An intensive drug treatment to kill cancer cells, but that also destroys the bone marrow and can cause other severe side effects. High-dose chemotherapy is usually followed by bone marrow or stem cell transplantation to rebuild the bone marrow.
  • high-dose radiation
  • An amount of radiation that is greater than that given in typical radiation therapy. High-dose radiation is precisely directed at the tumor to avoid damaging healthy tissue, and may kill more cancer cells in fewer treatments. Also called HDR.
  • high-dose-rate remote brachytherapy
  • A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote radiation therapy and remote brachytherapy.
  • high-dose-rate remote radiation therapy
  • A type of internal radiation treatment in which the radioactive source is removed between treatments. Also called high-dose-rate remote brachytherapy and remote brachytherapy.
  • high-energy photon therapy
  • A type of radiation therapy that uses high-energy photons (units of light energy). High-energy photons penetrate deeply into tissues to reach tumors while giving less radiation to superficial tissues such as the skin.
  • high-grade lymphoma
  • A type of lymphoma that grows and spreads quickly, and has severe symptoms. It is seen frequently in patients who are HIV-positive (AIDS-related lymphoma). Also called aggressive lymphoma and intermediate-grade lymphoma.
  • high-grade squamous intraepithelial lesion
  • Cells of the uterine cervix that are moderately or severely abnormal and may become cancer. Also called HSIL.
  • high-intensity focused ultrasound therapy
  • A procedure in which high-energy sound waves are aimed directly at an area of abnormal cells or tissue in the body. The waves create heat that kills the cells. High-intensity focused ultrasound therapy is being studied in the treatment of prostate cancer and some other types of cancer and other diseases. Also called HIFU.
  • highly active antiretroviral therapy
  • Treatment for human immunodeficiency virus (HIV) infection that uses a combination of several antiretroviral drugs. The drugs inhibit the ability of the virus to multiply in the body, and they slow down the development of AIDS. Also called HAART.
  • high-risk cancer
  • Cancer that is likely to recur (come back), or spread.
  • high-selenium Brassica juncea
  • Brassica juncea Brassica juncea Brassica juncea
  • hilar
  • Refers to the area where nerves and blood vessels attach to an organ.
  • HIPAA
  • A 1996 U.S. law that allows workers and their families to keep their health insurance when they change or lose their jobs. The law also includes standards for setting up secure electronic health records and to protect the privacy of a person’s health information and to keep it from being misused. Also called Health Insurance Portability and Accountability Act and Kassebaum Kennedy Act.
  • histamine dihydrochloride
  • A substance being studied in the treatment of some types of cancer and other conditions. When used together with interleukin-2, histamine dihydrochloride may help some immune cells find and kill tumor cells. It is a type of biological response modifier. Also called Maxamine.
  • histiocytic lymphoma
  • An outdated term referring to non-Hodgkin lymphomas made up of large abnormal lymphoid cells. Histiocytic lymphomas include mature B-cell and T-cell non-Hodgkin lymphomas. Many tumors that were once called histiocytic lymphomas are now considered to be a type of large cell lymphoma.
  • histologic examination
  • The examination of tissue specimens under a microscope.
  • histology
  • The study of tissues and cells under a microscope.
  • histone
  • A type of protein found in chromosomes. Histones bind to DNA, help give chromosomes their shape, and help control the activity of genes.
  • histone deacetylase
  • An enzyme that removes a small molecule called an acetyl group from histones (proteins found in chromosomes). This changes the way the histones bind to DNA and may affect its activity. Histone deacetylase inhibitors are being studied in the treatment of cancer. Also called HDAC.
  • histone deacetylase inhibitor
  • A substance that causes a chemical change that stops tumor cells from dividing. HDAC inhibitors are being studied in the treatment of cancer. Also called HDAC inhibitor.
  • histopathology
  • The study of diseased cells and tissues using a microscope.
  • historic cohort study
  • A research study in which the medical records of groups of individuals who are alike in many ways but differ by a certain characteristic (for example, female nurses who smoke and those who do not smoke) are compared for a particular outcome (such as lung cancer). Also called retrospective cohort study.
  • historical control subject
  • An individual treated in the past and used in a comparison group when researchers analyze the results of a clinical study that had no control group. The use of a control, or comparison, group helps researchers determine the effects of a new treatment more accurately.
  • HIV antibody
  • A substance produced by certain white blood cells in reaction to contact with the human immunodeficiency virus (HIV).
  • HIV positive
  • The cause of acquired immunodeficiency syndrome (AIDS). Also called human immunodeficiency virus.
  • hives
  • Itchy, raised red areas on the skin. Hives are caused by a reaction to certain foods, drugs, infections, or emotional stress. Also called urticaria.
  • HLA
  • One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and HLA tests are done before organ transplantation to find out if tissues match between a donor and a recipient. Also called human leukocyte antigen and human lymphocyte antigen.
  • HLH
  • A rare disorder in which histiocytes and lymphocytes (types of white blood cells) build up in organs including the skin, spleen, and liver, and destroy other blood cells. HLH may be inherited or caused by certain conditions or diseases, including infections, immunodeficiency (inability of the body to fight infections), and cancer. Also called hemophagocytic lymphohistiocytosis.
  • HLRCC
  • A rare inherited disorder that increases the risk of developing benign (not cancer) tumors of the skin and the uterus (leiomyomas) and malignant (cancer) tumors of the uterus (leiomyosarcoma) and the kidney. Also called hereditary leiomyomatosis and renal cell cancer syndrome.
  • HMGA1
  • A protein that binds to the DNA and certain proteins in chromosomes. It is involved in many functions in the cell, and helps protect cells from dying. HMGA1 is found at high levels in several types of cancer cells.
  • HMG-CoA reductase inhibitor
  • A substance that blocks an enzyme needed by the body to make cholesterol and lowers the amount of cholesterol in the blood. HMG-CoA reductase inhibitor drugs are called statins. Also called hydroxymethylglutaryl-coenzyme A reductase inhibitor.
  • HMR 1275
  • A substance being studied in the treatment of several types of cancer. It stops cells from dividing and may kill cancer cells. It is a type of cyclin-dependent kinase (CDK) inhibitor. Also called alvocidib and flavopiridol.
  • HNPCC
  • An inherited disorder in which affected individuals have a higher-than-normal chance of developing colorectal cancer and certain other types of cancer, often before the age of 50. Also called hereditary nonpolyposis colon cancer and Lynch syndrome.
  • Hodgkin disease
  • A cancer of the immune system that is marked by the presence of a type of cell called the Reed-Sternberg cell. The two major types of Hodgkin disease are classical Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. Symptoms include the painless enlargement of lymph nodes, spleen, or other immune tissue. Other symptoms include fever, weight loss, fatigue, or night sweats. Also called Hodgkin lymphoma.
  • Hodgkin lymphoma
  • A cancer of the immune system that is marked by the presence of a type of cell called the Reed-Sternberg cell. The two major types of Hodgkin lymphoma are classical Hodgkin lymphoma and nodular lymphocyte-predominant Hodgkin lymphoma. Symptoms include the painless enlargement of lymph nodes, spleen, or other immune tissue. Other symptoms include fever, weight loss, fatigue, or night sweats. Also called Hodgkin disease.
  • holmium Ho 166 DOTMP
  • A drug containing a radioactive isotope that is used in the diagnosis and treatment of cancer.
  • holy thistle
  • A plant whose leaves, stems, and flowers have been used in some cultures to treat certain medical problems. Holy thistle may have anti-inflammatory and anticancer effects. The scientific name is Cnicus benedictus . Also called blessed thistle, cardin, spotted thistle, and St. Benedict's thistle.
  • homeopathic medicine
  • An alternative approach to medicine based on the belief that natural substances, prepared in a special way and used most often in very small amounts, restore health. According to these beliefs, in order for a remedy to be effective, it must cause in a healthy person the same symptoms being treated in the patient. Also called homeopathy.
  • homeopathy
  • An alternative approach to medicine based on the belief that natural substances, prepared in a special way and used most often in very small amounts, restore health. According to these beliefs, in order for a remedy to be effective, it must cause in a healthy person the same symptoms being treated in the patient. Also called homeopathic medicine.
  • homeostasis
  • A state of balance among all the body systems needed for the body to survive and function correctly. In homeostasis, body levels of acid, blood pressure, blood sugar, electrolytes, energy, hormones, oxygen, proteins, and temperature are constantly adjusted to respond to changes inside and outside the body, to keep them at a normal level.
  • homeostatic
  • Having to do with homeostasis, which is a state of balance among all the body systems, needed for the body to function correctly.
  • homoharringtonine
  • An anticancer drug that belongs to the plant alkaloid family of drugs.
  • homozygous genotype
  • Occurs when both alleles at a particular gene locus are the same. A person may be homozygous for the normal allele or for a mutation.
  • hormonal therapy
  • Treatment that adds, blocks, or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones. Sometimes surgery is needed to remove the gland that makes a certain hormone. Also called endocrine therapy, hormone therapy, and hormone treatment.
  • hormone receptor
  • One of many chemicals made by glands in the body. Hormones circulate in the bloodstream and control the actions of certain cells or organs. Some hormones can also be made in the laboratory.
  • hormone receptor test
  • A test to measure the amount of certain proteins, called hormone receptors, in cancer tissue. Hormones can attach to these proteins. A high level of hormone receptors may mean that hormones help the cancer grow.
  • hormone replacement therapy
  • Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called HRT and menopausal hormone therapy.
  • hormone responsive
  • In oncology, describes cancer that responds to hormone treatment.
  • hormone therapy
  • Treatment that adds, blocks, or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones. Sometimes surgery is needed to remove the gland that makes a certain hormone. Also called endocrine therapy, hormonal therapy, and hormone treatment.
  • hormone treatment
  • Treatment that adds, blocks, or removes hormones. For certain conditions (such as diabetes or menopause), hormones are given to adjust low hormone levels. To slow or stop the growth of certain cancers (such as prostate and breast cancer), synthetic hormones or other drugs may be given to block the body’s natural hormones. Sometimes surgery is needed to remove the gland that makes a certain hormone. Also called endocrine therapy, hormonal therapy, and hormone therapy.
  • Horner syndrome
  • A condition in which one side of the face is flushed, does not produce sweat, and has a constricted pupil and drooping eyelid. It can be caused by an injury to, or paralysis of, nerves in the neck, or by a tumor.
  • hospice
  • A program that provides special care for people who are near the end of life and for their families, either at home, in freestanding facilities, or within hospitals.
  • host cell
  • A cell that is infected by a virus or another type of microorganism.
  • hot flash
  • A sudden, temporary onset of body warmth, flushing, and sweating (often associated with menopause).
  • hot nodule
  • When radioactive material is used to examine the thyroid with a scanner, nodules that collect more radioactive material than the surrounding thyroid tissue are considered "hot." Hot nodules are rarely malignant. Hot nodules are sometimes called hyperfunctioning nodules.
  • hotspot
  • In genetics, an area of DNA that is likely to mutate (change).
  • HPPH
  • 2-(1-hexyloxyethyl)-2-devinyl pyropheophorbide-a. A drug that is used in photodynamic therapy that is absorbed by tumor cells; when exposed to light, it becomes active and kills the cancer cells.
  • HPV
  • A type of virus that can cause abnormal tissue growth (for example, warts) and other changes to cells. Infection for a long time with certain types of HPV can cause cervical cancer. HPV can also play a role in some other types of cancer, such as anal, vaginal, vulvar, penile, and oropharyngeal cancers. Also called human papillomavirus.
  • HPV 16/18 L1 VLP/AS04 VAC
  • A vaccine used to prevent cervical cancer, cervical intraepithelial neoplasia, and adenocarcinoma caused by human papillomaviruses (HPV) types 16 and 18. HPV 16/18 L1 VLP/AS04 VAC is approved to be given to females aged 10-25 years. It is also being studied in the treatment of other medical conditions. It is a type of bivalent vaccine. Also called Cervarix, GSK-580299, and human papillomavirus 16/18 L1 virus-like particle/AS04 vaccine.
  • HPV vaccine
  • A vaccine being studied in the prevention of human papillomavirus infection and cervical cancer. Infection with certain types of HPV increases the risk of developing cervical cancer. Also called human papillomavirus vaccine.
  • HRT
  • Hormones (estrogen, progesterone, or both) given to women after menopause to replace the hormones no longer produced by the ovaries. Also called hormone replacement therapy and menopausal hormone therapy.
  • HSIL
  • Cells of the uterine cervix that are moderately or severely abnormal and may become cancer. Also called high-grade squamous intraepithelial lesion.
  • HSP
  • One of a group of proteins that help protect cells from stresses such as heat, cold, and low amounts of oxygen or glucose (sugar). HSPs help other proteins function in normal cells and may be present at high levels in cancer cells. Blocking the activity of a HSP called HSP90 is being studied in the treatment of cancer. Other HSPs including HSP70 and gp96 are being studied in vaccines to treat cancer. Also called heat-shock protein and stress protein.
  • HSV
  • A type of virus that causes herpes infections and has DNA as its genetic material. There are two types of HSVs. Infections with type 1 viruses cause cold sores on the lips or nostrils. Infections with type 2 viruses cause sores on the genitals (external and internal sex organs and glands). Also called herpes simplex virus, HHV, and human herpesvirus.
  • HTLV-1
  • A type of virus that infects T cells (a type of white blood cell) and can cause leukemia and lymphoma. HTLV-1 is spread by sharing syringes or needles, through blood transfusions or sexual contact, and from mother to child during birth or breast-feeding. Also called human T-cell leukemia virus type 1 and human T-cell lymphotropic virus type 1.
  • hu14.18-interleukin-2 fusion protein
  • An anticancer drug in which hu14.18, a monoclonal antibody, is combined with interleukin-2. The monoclonal antibody binds to the cancer cells and delivers IL-2, which stimulates the immune system to destroy the cancer cells.
  • Hu3S193
  • A monoclonal antibody that is being studied in the treatment of some types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. Hu3S193 binds to the protein Lewis(y), which is found on colon, breast, lung, ovary, and prostate cancer cells.
  • HuAFP31
  • A monoclonal antibody being studied in the treatment of several types of cancer. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. HuAFP31 attaches to tumor cells that make alpha fetoprotein (AFP). This makes it easier for T cells to find and kill the tumor cells.
  • Huang Lian
  • A Chinese herb that has been used as a treatment for a variety of medical problems. It is being studied as an anticancer drug.
  • huC242-DM4
  • A substance being studied in the treatment of some types of cancer. It is made by linking the monoclonal antibody huC242 to a toxic substance called maytansinoid DM4. The monoclonal antibody locates and binds to the surfaces of cancer cells and the maytansinoid DM4 enters the cells and blocks their growth. It is a type of immunotoxin. Also called maytansinoid DM4-conjugated humanized monoclonal antibody huC242.
  • HuHMFG1
  • A monoclonal antibody that binds to the protein MUC1, which is found on breast, ovarian, pancreatic, gastric, and colon cancer cells. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. HuHMFG1 is being studied in the treatment of some types of cancer.
  • HuLuc63
  • A monoclonal antibody being studied in the treatment of advanced multiple myeloma. Monoclonal antibodies are made in the laboratory and can locate and bind to substances in the body, including cancer cells. HuLuc63 binds to CS1, a protein that is found mainly on the surface of multiple myeloma cells.
  • human corticotropin-releasing factor
  • A substance being studied in the treatment of brain cancer. It is made naturally by the hypothalamus (a part of the brain) and can also be made in the laboratory. Human corticotropin-releasing factor may help reduce symptoms caused by edema (swelling) of the brain. It is a type of neurohormone. Also called hCRF.
  • human EGF receptor 2
  • A protein involved in normal cell growth. It is found on some types of cancer cells, including breast and ovarian. Cancer cells removed from the body may be tested for the presence of human EGF receptor 2 to help decide the best type of treatment. Human EGF receptor 2 is a type of receptor tyrosine kinase. Also called c-erbB-2, HER2/neu, and human epidermal growth factor receptor 2.
  • human epidermal growth factor receptor 2
  • A protein involved in normal cell growth. It is found on some types of cancer cells, including breast and ovarian. Cancer cells removed from the body may be tested for the presence of human epidermal growth factor receptor 2 to help decide the best type of treatment. Human epidermal growth factor receptor 2 is a type of receptor tyrosine kinase. Also called c-erbB-2, HER2/neu, and human EGF receptor 2.
  • human herpesvirus 8
  • A type of virus that causes herpes infections and has DNA as its genetic material. There are two types of human herpesviruses. Infections with type 1 viruses cause cold sores on the lips or nostrils. Infections with type 2 viruses cause sores on the genitals (external and internal sex organs and glands). Also called herpes simplex virus, HHV, and HSV.
  • human immunodeficiency virus
  • The cause of acquired immunodeficiency syndrome (AIDS). Also called HIV.
  • human leukocyte antigen
  • One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and human leukocyte antigen tests are done before organ transplantation to find out if tissues match between a donor and a recipient. Also called HLA and human lymphocyte antigen.
  • human lymphocyte antigen
  • One of a group of proteins found on the surface of white blood cells and other cells that play an important part in the body's immune response to foreign substances. These antigens vary from person to person, and HLA tests are done before organ transplantation to find out if tissues match between a donor and a recipient. Also called HLA and human leukocyte antigen.
  • human papillomavirus 16/18 L1 virus-like particle/AS04 vaccine
  • A vaccine used to prevent cervical cancer, cervical intraepithelial neoplasia, and adenocarcinoma caused by human papillomaviruses (HPV) types 16 and 18. Human papillomavirus 16/18 L1 virus-like particle/AS04 vaccine is approved to be given to females aged 10-25 years. It is also being studied in the treatment of other medical conditions. It is a type of bivalent vaccine. Also called Cervarix, GSK-580299, and HPV 16/18 L1 VLP/AS04 VAC.
  • human papillomavirus vaccine
  • A type of virus that can cause abnormal tissue growth (for example, warts) and other changes to cells. Infection for a long time with certain types of human papillomavirus can cause cervical cancer. Human papillomavirus can also play a role in some other types of cancer, such as anal, vaginal, vulvar, penile, and oropharyngeal cancers. Also called HPV.
  • human participant protection regulations
  • Laws set by the U.S. Department of Health and Human Services (DHHS) to protect a person from risks in research studies that any federal agency or department has a part in. Also called 45 CFR 46, 45 Code of Federal Regulations Part 46, and Protection of Human Subjects.
  • human T-cell leukemia virus type 1
  • A type of virus that infects T cells (a type of white blood cell) and can cause leukemia and lymphoma. Human T-cell leukemia virus type 1 is spread by sharing syringes or needles, through blood transfusions or sexual contact, and from mother to child during birth or breast-feeding. Also called HTLV-1 and human T-cell lymphotropic virus type 1.
  • human T-cell lymphotropic virus type 1
  • A type of virus that infects T cells (a type of white blood cell) and can cause leukemia and lymphoma. Human T-cell lymphotropic virus type 1 is spread by sharing syringes or needles, through blood transfusions or sexual contact, and from mother to child during birth or breast-feeding. Also called HTLV-1 and human T-cell leukemia virus type 1.
  • humanized monoclonal antibody
  • A type of antibody made in the laboratory by combining a human antibody with a small part of a mouse or rat monoclonal antibody. The mouse or rat part of the antibody binds to the target antigen, and the human part makes it less likely to be destroyed by the body's immune system.
  • humanized monoclonal antibody MEDI-522
  • A substance being studied in the treatment of some types of cancer and other conditions. Humanized monoclonal antibody MEDI-522 binds to a protein on the surface of blood vessels and may prevent the growth of new blood vessels that tumors need to grow. It may also prevent the spread of cancer. It is a type of antiangiogenesis agent, a type of metastasis inhibitor, and a type of monoclonal antibody. Also called Abegrin, etaracizumab, and MEDI-522.
  • HuMax-CD20
  • A drug used to treat chronic lymphocytic leukemia (CLL) that has not gotten better with other chemotherapy. It is also being studied in the treatment of other types of cancer, including follicular non-Hodgkin lymphoma. HuMax-CD20 binds to CD20, a protein on the surface of normal B cells and most B-cell tumors. This may kill the cancer cells. It is a type of monoclonal antibody. Also called Arzerra and ofatumumab.
  • humidifier
  • A machine that puts moisture in the air.
  • Hurthle cell neoplasm
  • An uncommon type of thyroid tumor that can be benign or malignant.
  • Hycamtin
  • A drug used to treat certain types of ovarian cancer, lung cancer, and cervical cancer. Hycamtin is a type of topoisomerase inhibitor. Also called topotecan and topotecan hydrochloride.
  • hydatidiform mole
  • A slow-growing tumor that develops from trophoblastic cells (cells that help an embryo attach to the uterus and help form the placenta) after fertilization of an egg by a sperm. A hydatidiform mole contains many cysts (sacs of fluid). It is usually benign (not cancer) but it may spread to nearby tissues (invasive mole). It may also become a malignant tumor called choriocarcinoma. Hydatidiform mole is the most common type of gestational trophoblastic tumor. Also called molar pregnancy.
  • hydration
  • The process of combining with water. In medicine, the process of giving fluids needed by the body.
  • hydrazine sulfate
  • A substance that has been studied as a treatment for cancer and as a treatment for cachexia (body wasting) associated with advanced cancer.
  • hydrocephalus
  • The abnormal buildup of cerebrospinal fluid in the ventricles of the brain.
  • hydrocodone bitartrate
  • A drug used to treat moderate to severe pain and cough. Hydrocodone bitartrate is made from codeine and binds to opioid receptors in the central nervous system. It is a type of analgesic agent, a type of antitussive, and a type of opiate.
  • hydrocortisone
  • A drug used to relieve the symptoms of certain hormone shortages and to suppress an immune response.
  • hydrogen peroxide
  • A chemical used in bleaches, dyes, cleansers, antiseptics, and disinfectants. In a concentrated form, it is toxic and irritating to tissues.
  • hydrolysis
  • A chemical reaction that uses water to break down a compound.
  • hydromorphone
  • A drug used to relieve pain.
  • hydronephrosis
  • Abnormal enlargement of a kidney, which may be caused by blockage of the ureter (such as by a kidney stone) or chronic kidney disease that prevents urine from draining into the bladder.
  • hydroureter
  • Abnormal enlargement of the ureter caused by any blockage that prevents urine from draining into the bladder.
  • hydroxychloroquine
  • A substance that decreases immune responses in the body. It is used to treat some autoimmune diseases, and is being studied as a treatment for graft-versus-host disease. Hydroxychloroquine belongs to the family of drugs called antiprotozoals.
  • hydroxydaunorubicin
  • A drug that is used to treat many types of cancer and is being studied in the treatment of other types of cancer. Hydroxydaunorubicin comes from the bacterium Streptomyces peucetius . It damages DNA and may kill cancer cells. It is a type of anthracycline antitumor antibiotic. Also called Adriamycin PFS, Adriamycin RDF, doxorubicin, doxorubicin hydrochloride, and Rubex.
  • hydroxymethylglutaryl-coenzyme A reductase inhibitor
  • A substance that blocks an enzyme needed by the body to make cholesterol and lowers the amount of cholesterol in the blood. Hydroxymethylglutaryl-coenzyme A reductase inhibitor drugs are called statins. Also called HMG-CoA reductase inhibitor.
  • hydroxyurea
  • An anticancer drug that belongs to the family of drugs called antimetabolites.
  • hygiene
  • The science of health, and the practice of cleanliness that promotes good health and well-being.
  • hyperactivity
  • A higher than normal level of activity. Hyperactivity can be used to describe the increased action of a body function, such as hormone production, or behavior. A person who is hyperactive may seem to be always moving or fidgeting, impulsive, unable to concentrate, and talking too much.
  • hyperalimentation
  • A form of nutrition that is delivered into a vein. Hyperalimentation does not use the digestive system. It may be given to people who are unable to absorb nutrients through the intestinal tract because of vomiting that won't stop, severe diarrhea, or intestinal disease. It may also be given to those undergoing high-dose chemotherapy or radiation and bone marrow transplantation. It is possible to give all of the protein, calories, vitamins and minerals a person needs using hyperalimentation. Also called parenteral nutrition, total parenteral nutrition, and TPN.
  • hyperbaric oxygen
  • Oxygen that is at an atmospheric pressure higher than the pressure at sea level. Breathing hyperbaric oxygen to enhance the effectiveness of radiation therapy is being studied.
  • hypercalcemia
  • Higher than normal levels of calcium in the blood. Some types of cancer increase the risk of hypercalcemia.
  • hyperfractionated radiation therapy
  • Radiation treatment in which the total dose of radiation is divided into small doses and treatments are given more than once a day. Also called hyperfractionation and superfractionated radiation therapy.
  • hyperfractionation
  • Radiation treatment in which the total dose of radiation is divided into small doses and treatments are given more than once a day. Also called hyperfractionated radiation therapy and superfractionated radiation therapy.
  • hyperglycemia
  • Higher than normal amount of glucose (a type of sugar) in the blood. Hyperglycemia can be a sign of diabetes or other conditions. Also called high blood sugar.
  • Hypericum perforatum
  • An herbal product sold as an over-the-counter treatment for depression. It is being studied for its ability to lessen certain side effects of cancer treatment. Also called St. John's wort.
  • hyperkeratosis
  • A condition marked by thickening of the outer layer of the skin, which is made of keratin (a tough, protective protein). It can result from normal use (corns, calluses), chronic inflammation (eczema), or genetic disorders (X-linked ichthyosis, ichthyosis vulgaris).
  • hypernephroma
  • The most common type of kidney cancer. It begins in the lining of the renal tubules in the kidney. The renal tubules filter the blood and produce urine. Also called renal cell adenocarcinoma, renal cell cancer, and renal cell carcinoma.
  • hyperparathyroidism
  • A condition in which the parathyroid gland (one of four pea-sized organs found on the thyroid) makes too much parathyroid hormone. This causes a loss of calcium from the bones and an increased level of calcium in the blood. Symptoms include bone pain and kidney problems.
  • hyperplasia
  • An abnormal increase in the number of normal cells in an organ or tissue.
  • hypersensitivity
  • An exaggerated response by the immune system to a drug or other substance.
  • hypertension
  • A blood pressure of 140/90 or higher. Hypertension usually has no symptoms. It can harm the arteries and cause an increase in the risk of stroke, heart attack, kidney failure, and blindness. Also called high blood pressure.
  • hyperthermia therapy
  • Abnormally high body temperature. This may be caused as part of treatment, by an infection, or by exposure to heat.
  • hyperthermic perfusion
  • A procedure in which a warmed solution containing anticancer drugs is used to bathe, or is passed through the blood vessels of, the tissue or organ containing the tumor.
  • hyperthyroidism
  • Too much thyroid hormone. Symptoms include weight loss, chest pain, cramps, diarrhea, and nervousness. Also called overactive thyroid.
  • hyperuricemia
  • A buildup of uric acid (a byproduct of metabolism) in the blood. Hyperuricemia is a side effect of some anticancer drugs.
  • hypervascular
  • Having a large number of blood vessels.
  • hypnosis
  • A trance-like state in which a person becomes more aware and focused and is more open to suggestion.
  • hypofractionated radiation therapy
  • Radiation treatment in which the total dose of radiation is divided into large doses and treatments are given less than once a day. Also called hypofractionation.
  • hypofractionation
  • Radiation treatment in which the total dose of radiation is divided into large doses and treatments are given less than once a day. Also called hypofractionated radiation therapy.
  • hypogammaglobulinemia
  • A condition in which the level of immunoglobulins (antibodies) in the blood is low and the risk of infection is high.
  • hypoglycemia
  • Abnormally low blood sugar.
  • hypopharyngeal cancer
  • Cancer that forms in tissues of the hypopharynx (the bottom part of the throat). The most common type is squamous cell carcinoma (cancer that begins in flat cells lining the hypopharynx).
  • hypopharynx
  • The bottom part of the throat. Cancer of the hypopharynx is also known as hypopharyngeal cancer.
  • hypospadias
  • A birth defect in which the opening of the urethra (the tube through which urine leaves the body) is not in its normal place. In males with hypospadias, the urethra opens on the underside of the penis or between the anus and the scrotum. In females with hypospadias, it opens into the vagina. Hypospadias is much more common in males than in females, and can be corrected by surgery. Children with hypospadias have an increased risk of developing Wilms tumor (a type of kidney cancer).
  • hypotension
  • Abnormally low blood pressure.
  • hypothalamus
  • The area of the brain that controls body temperature, hunger, and thirst.
  • hypothesis
  • A tentative proposal made to explain certain observations or facts that requires further investigation to be verified.
  • hypothyroidism
  • Too little thyroid hormone. Symptoms include weight gain, constipation, dry skin, and sensitivity to the cold. Also called underactive thyroid.
  • hypoxemia
  • A condition in which there is not enough oxygen in the blood.
  • hypoxia
  • A condition in which there is a decrease in the oxygen supply to a tissue. In cancer treatment, the level of hypoxia in a tumor may help predict the response of the tumor to the treatment.
  • hypoxic
  • Having too little oxygen.
  • hysterectomy
  • Surgery to remove the uterus and, sometimes, the cervix. When the uterus and the cervix are removed, it is called a total hysterectomy. When only the uterus is removed, it is called a partial hysterectomy.
  • Hytrin
  • A drug used to treat urinary problems caused by an enlarged prostate. It is also used to treat high blood pressure and is being studied in the treatment of other conditions. Hytrin relaxes muscle tissue in blood vessels and in the prostate. It is a type of alpha blocker. Also called terazosin and terazosin hydrochloride.
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