Medical Glossary H
Hair follicles (FOL-i-kuls): The sacs in the scalp from which hair grows.
Hairy cell leukemia: A rare type of chronic leukemia in which the abnormal white blood cells appear to be covered with tiny hairs.
Helicobacter pylori (HEEL-i-ko-BAK-ter pie-LOR-ee): Bacteria that cause inflammation and ulcers in the stomach.
Hematogenous: Orginating in the blood, or disseminated by the circulation or through the bloodstream.
Hematologist (hee-ma-TOL-o-jist): A doctor who specializes in treating diseases of the blood.
Hepatitis (hep-a-TYE-tis): Inflammation of the liver.
Hepatitis B: A type of hepatitis that is carried and passed on through the blood. It can be passed on through sexual contact or through the use of "dirty" (bloody) needles.
Hepatoblastoma (HEP-a-to-blas-TO-ma): A type of liver tumor that occurs in infants and children.
Hepatocellular carcinoma (HEP-a-to-SEL-yoo-ler kar-si-NO-ma): The most common type of primary liver cancer.
Hepatocyte (HEP-a-to-site): A liver cell.
Hepatoma (HEP-a-TO-ma): A liver tumor.
Hereditary mutation: A gene change in the body's reproductive cells (egg or sperm) that becomes incorporated into the DNA of every cell in the body of offspring; hereditary mutations are passed on from parents to offspring.
Herpes virus (HER-peez-VY-rus): A member of the herpes family of viruses. One type of herpesvirus is sexually transmitted and causes sores on the genitals.
HER-2/neu: Oncogene found in some breast and ovarian cancer patients that is associated with a poor prognosis.
Hormonal therapy: Treatment of cancer by removing, blocking, or adding hormones.
Hormone receptor test: A test to measure the amount of certain proteins, called hormone receptors, in breast cancer tissue. Hormones can attach to these proteins. A high level of hormone receptors means hormones probably help the cancer grow.
Hormones: Chemicals produced by glands in the body and circulate in the bloodstream. Hormones control the actions of certain cells or organs.
Human papillomaviruses (pap-i-LOW-ma VY-rus-ez): Viruses that generally cause warts. Some papillomaviruses are sexually transmitted. Some of these sexually transmitted viruses cause wartlike growths on the genitals, and some are thought to cause abnormal changes in cells of the cervix.
Humidifier (hyoo-MID-ih-fye-er): A machine that puts moisture in the air.
Hydrocephalus (hy-dro-SEF-uh-lus): The abnormal buildup of cerebrospinal fluid in the ventricles of the brain.
Hypercalcemia (hy-per-kal-SEE-mee-a): A higher-than-normal level of calcium in the blood. This condition can cause a number of symptoms, including loss of appetite, nausea, thirst, fatigue, muscle weakness, restlessness and confusion.
Hyperfractionation: A way of giving radiation therapy in smaller-than-usual doses two or three times a day.
Hyperplasia (hye-per-PLAY-zha): A precancerous condition in which there is an increase in the number of normal cells lining the uterus.
Hyperthermia (hy-per-THER-mee-a): Treatment that involves heating a tumor.
Hypothalamus (hy-po-THAL-uh-mus): The area of the brain that controls body temperature, hunger, and thirst.
Hysterectomy (hiss-ter-EK-to-mee): An operation in which the uterus and cervix are removed.