Health-care proxies   
A legal document that authorizes someone other than the patient to make decisions for the patient about health issues when necessary.

Hematocrit    (Hct)
The percentage of red blood cells in the blood.

Hematologist   
A doctor who specializes in the problems of blood and bone marrow.

Hematology   
The science that studies the blood.

Hematuria   
Blood in the urine.

Hemoccult (Guaiac test)   
A test that checks for hidden blood in the stool.

Hemoptysis   
Coughing up any amount of blood.

Hemorrhoids   
Veins near the anus that can become swollen and painful and sometimes bleed.

Hereditary risk factor   
Altered or mutated genes that make it more likely that a person will develop cancer.

Herpes simplex   
The most common virus that causes sores often seen around the mouth. Commonly called a cold sore.

Herpes zoster   
A virus that settles around certain nerves causing blisters, swelling, and pain. This condition is also called shingles.

Hoarseness   
Raspy voice.

Hodgkin’s disease   
A cancer that affects the lymph nodes. See Lymphoma.

Hormone   
A substance that regulates growth, metabolism, and reproduction and is secreted by various organs in the body.

Horner’s syndrome   
Symptoms (a small pupil, a droopy eyelid, and absence of sweating all on one side of the face) signifying dysfunction of the sympathetic nerve on that side of the body.

Hospice   
A concept of supportive care to meet the special needs of patients and family during the terminal stages of illness. The care may be delivered in the home or hospital by a specially trained team of professionals.

Human Immunodeficiency Virus    (HIV)
Human Immunodeficiency Virus (HIV): The virus that causes AIDS.

Human Leukocyte Antigen test   (HLA)
A special blood test used to match a blood or bone marrow donor to a recipient for transfusion or transplant.

Hyperalimentation   
The intravenous administration of a highly nutritious solution.

Hyperplasia   
An abnormal increase in the number of cells in an otherwise normal tissue.

Hypnotherapy   
The use of hypnosis in the treatment of disease.

Hysterectomy   
Surgical removal of the uterus.