Medical Dictionary Definitions A-Z List
Medical Dictionary Definitions A - Z - «H»:
Hirudotherapy: The use of leeches for medical therapy. Sometimes referred to as the "treatment that sucks."
From hirudin, the active principle in the salivary secretion of leeches that acts as a potent anticoagulant (bloodthinner)....
His: Histidine. See also: Amino acid symbols....
His disease: This is a parasite (louse-borne) disease that was first recognized in the trenches of World War I and so was called trench fever. It is estimated to have affected more than a million people in Russia and on the war fronts in Europe. Trench fever was again a major problem in the military...
His-Werner disease: This is a parasite (louse-borne) disease that was first recognized in the trenches of World War I and so was called trench fever. It is estimated to have affected more than a million people in Russia and on the war fronts in Europe. Trench fever was again a major problem in the m...
Histamine: Substance that plays a major role in many allergic
reactions. Histamine dilates blood vessels and makes the vessel walls abnormally
Histamine cephalalgia: A
distinctive syndrome of headaches, also known as cluster
headache or migrainous neuralgia. The common pattern of
cluster headache is termed "episodic" and is characterized
by 1-3 short attacks of pain each day around the eyes,
clustered over a stretch of 1-2 months, f...
Histidine: An amino acid, one of the 20 building blocks of protein. An essential amino acid, histidine is present in many proteins. Histidine is elevated in the blood and urine in a genetic condition called histidinemia. Decarboxylation of histidine results in the formation of histamine. Symbol: His...
Histiocyte: A type of white blood cell, also
called a macrophage, that is created by the bone marrow.
They usually stay in place, but when histiocytes are
stimulated by infection or inflammation they become active,
attacking bacteria and other foreign matter in the body.
See also histiocytosis....
Histiocytic necrotizing lymphadenitis
Histiocytic necrotizing lymphadenitis: A disorder, also called Kikuchi disease, that typically causes "swollen glands" in the neck (cervical lymphadeniopathy) together with fever or flu-like symptoms. Laboratory test abnormalities include elevated erythrocyte sedimentation rate (ESR), and white blo...
Histiocytosis: A rare but potentially deadly
disorder with similarities to cancer, in which histiocytes
start to multiply and attack the person's own tissues or
organs. The result can be tissue damage, pain, development
of tumor-like lumps called granulomas, fatigue, and other
symptoms. If hist...
Histiocytosis X: Now called Langerhans cell histiocytosis. This disease is subclassified into eosinophilic granuloma, Letterer Siwe disease, and Hand-Schuller-Christian disease....
Histiocytosis, Hand-Schuller-Christian: A disease in which histiocytes start to multiply
and attack the tissues or organs of the patient. The disease usually affects
children age 2 to 5, less often older children and adults. The most frequent
sites of bony involvement are the flat bones of the sk...
Histiocytosis, Langerhans cell
cell: Histiocytosis in which the active histiocytes normally occur in the
Histiocytosis, Letterer Siwe
Histiocytosis, Letterer Siwe: A severe disease in which histiocytes start to multiply and attack the tissues or organs of the patient starting in infancy with a scaly, sometimes itchy rash on the scalp, ears, abdomen, and creases of the neck and face. Raw skin may provide a portal of entry for germs...
Histiocytosis, lipid: A form of histiocytosis
that affects lipid (fat) storage. Also known as Niemann-
Pick disease, Erdheim-Chester disease....