DEFINITION Morning sickness is nausea that occurs during pregnancy. The name is a misnomer, however, since morning sickness can strike at any time of the day or night. Morning sickness affects a large proportion of pregnant women. It is most…
DEFINITION If you have a mood disorder, your general emotional state or mood is distorted or inconsistent with your circumstances. Some examples of mood disorders include: Major depressive disorder — prolonged and persistent periods of extreme sadness …
DEFINITION Monoclonal gammopathy of undetermined significance (MGUS) is a condition in which an abnormal protein (monoclonal protein, or M protein) is in the blood. M protein is produced by plasma cells, a type of white blood cell. Monoclonal gammopathy of…
DEFINITION Molluscum contagiosum (mo-LUS-kum kun-tay-jee-OH-sum) is a relatively common viral infection of the skin that results in round, firm, painless bumps ranging in size from a pinhead to a pencil eraser. If the bumps are scratched or injured, the infection…
DEFINITION If you have a mold allergy, your immune system overreacts when you breathe in mold spores. This triggers a cascade of reactions that lead to allergic symptoms. Like other allergies, a mold allergy can make you cough, make your…
DEFINITION A molar pregnancy — also known as hydatidiform mole — is a noncancerous (benign) tumor that develops in the uterus. A molar pregnancy starts when an egg is fertilized, but instead of a normal, viable pregnancy resulting, the placenta…
DEFINITION Mesenteric ischemia (mez-un-TER-ik is-KEE-me-uh) is a condition caused by poor blood supply to your intestines. Mesenteric ischemia usually affects the small intestine, colon or both. It may also involve other organs in the digestive system. Mesenteric ischemia may be…
DEFINITION Lymphadenitis is a condition in which your lymph nodes — tissues that help your body fight off illness — become inflamed. Mesenteric lymphadenitis (mez-un-TER-ik lim-fad-uh-NIE-tis) is an inflammation of the lymph nodes in the membrane that attaches your intestine…
DEFINITION Malignant mesothelioma (me-zoe-thee-lee-O-muh) is a rare cancer that occurs in the thin layer of tissue that covers the majority of your internal organs (mesothelium). Mesothelioma is an aggressive and deadly form of cancer. Mesothelioma treatments are available, but for…
DEFINITION Metabolic syndrome is a cluster of conditions — increased blood pressure, a high blood sugar level, excess body fat around the waist and abnormal cholesterol levels — that occur together, increasing your risk of heart disease, stroke and diabetes.…
DEFINITION In metachromatic leukodystrophy, a rare hereditary (genetic) disorder, deficiency of an enzyme that helps break down fatty substances (lipids) causes lipids to build up in your brain, spinal cord and peripheral nerves. As a result, your brain and nervous…
DEFINITION Microcephaly (my-kroh-SEF-uh-lee) is a rare neurological condition in which an infant’s head is significantly smaller than the heads of other children of the same age and sex. Sometimes detected at birth, microcephaly usually is the result of the brain…