Category: H

Inflammation of the liver due to infection with the hepatitis E virus (HEV). This virus is also known as epidemic non-A, non-B hepatitis; it is transmitted through the intestinal tract. No outbreaks of HEV have occurred in the United States. The disease occurs mainly in areas with poor sanitation. Epidemics have been reported in Asia…

A disease most commonly caused by Rh incompatibility, a situation in which the mother’s blood develops antibodies in reaction to the blood of the fetus. The disease occurs when an Rh-negative mother is pregnant with an Rh-positive fetus; the fetus can develop anemia from the loss of red blood cells and jaundice from its body’s…

Blood in the semen. Hematospermia is occasionally associated with other symptoms, including pain with urination, ejaculation, or bowel movement; swelling or tenderness in the groin or scrotum; back pain; and fever. The condition may be a sign of prostate cancer or of infection, obstruction, or injury in the male reproductive tract. Treatment depends on the…

An operation to repair or replace one of the four valves in the heart. In the normally functioning heart, the flaps of each of the four valves—pulmonary, mitral, aortic, and tricuspid— allow blood to flow in only one direction as it travels to and from the lungs and to and from the body. Stenosis (narrowing)…

A broad category of tumors that arise in the head and neck area, including tumors in the mouth, tongue, lips, gums, sinuses, salivary glands, throat, and larynx (voice box). Symptoms can include swelling or sores in the mouth that do not heal; pain, swelling, or obstruction of the nose; chronic sinus trouble that is unresponsive…

A slowly developing and persistent autoimmune disease caused by the action of certain antibodies that attack the tissues of the thyroid gland; also known as chronic lymphocytic or autoimmune thyroiditis. Hashimoto thyroiditis can eventually cause hypothyroidism (underactivity of the thyroid gland). In Hashimoto thyroiditis, thyroid tissue is invaded by white blood cells called lymphocytes. The…

An injury involving a strain in one or more of the three muscles located at the back of the thigh. The hamstring muscles run between the buttock and the knee, where they are connected to the bones of the lower leg. A hamstring pull often occurs following participation in strenuous sports or other activities involving…

Chemical substances that can alter a person’s perception of reality and cause hallucinations and other alterations of the senses. Hallucinogenic substances occur naturally in plants, fungi, and animals; and they have been used throughout history in a wide variety of highly advanced and preliterate cultures. A hallucinogen is a type of drug that induces hallucinations.…

A surgical procedure to remove small portions of hair-bearing scalp and relocate them to a bald area on the head of a person. Hair transplants are usually performed as cosmetic surgery for the baldness that develops as a result of aging, hormonal changes, or from a family history of hair loss. Hair transplantation can also…

Excess hair may be due to elevated androgen levels or an underlying endocrine disorder, which should be treated with appropriate medication. There are other causes. Hair can be removed for cosmetic reasons by shaving with a shaver or razor (which may cause problems such as skin irritation or infected hair follicles), using depilatories (chemical hair…