Health A-Z

H. Pylori Infection

Clinical Definition H. pylori is a bacterium that can infect the stomach or duodenum (first part of the small intestine), causing inflammation, irritation and ulcers. Infection with H. pylori is also a risk factor for some gastric cancers. The infection can be treated with antibiotics and acid-reducing medication. In Our Own Words H. pylori bacteria

Hairy Cell Leukemia

Clinical Definition Hairy cell leukemia (HCL) is a cancer of the bone and blood marrow characterized by the bone marrow overproducing lymphocytes. The rare cancer either progresses slowly or not at all, with fever, weakness and fever among the symptoms. Treatments may include chemotherapy, surgery, stem cell transplants or biologic therapy to boost the immune


Clinical Definition Halitosis is a dental health condition characterized by odorous breath. It may occur due to oral pathology, such as poor oral hygiene, dental infections and gum disease. Some systemic diseases, such as renal and kidney disease, may also cause halitosis. In other instances, halitosis is the result of ingestion of certain foods. In


Clinical Definition Hammertoe or hammertoe syndrome describes a sometimes-painful condition in which a toe bends, curling up and under, resembling a hammer. The toe is initially still flexible, but as the condition progresses, it may become rigid and require surgical intervention. In Our Own Words Hammertoe, also called hammertoe syndrome, can be caused by a

Hashimoto’s Disease

Clinical Definition Hashimoto’s disease, or chronic thyroiditis, is a common thyroid gland disorder triggered by an autoimmune reaction against the thyroid gland, which can prevent it from producing sufficient amounts of thyroid hormone. Signs and symptoms of thyroid deficiency include poor concentration, temperature intolerance, and weight gain. Diagnosis is aided by blood tests that measure

Hay Fever

Clinical Definition Hay fever, also called seasonal allergic rhinitis or simply rhinitis, is the most prevalent type of allergy. It is caused by an IgE-mediated immune response to allergens that are airborne and inhaled. The condition is marked by sneezing, a runny nose and itching. Avoiding exposure to the allergen; taking over-the-counter or prescription medicines;

Heart Ventricles

Clinical Definition The ventricles are the two lower chambers of the heart. In Our Own Words The heart is divided in two halves by a wall or septum. Each half of the heart has a smaller upper chamber (atrium) and a larger lower chamber (ventricle). The ventricles receive blood from the atria. The right half

Heat Exhaustion

Clinical Definition Heat exhaustion is a reaction to prolonged exposure to high temperatures. It develops due to a depletion of electrolytes and dehydration without adequate replenishment. It is characterized by weakness, prostration and tachycardia. If heat exposure is allowed to continue, the condition may progress into heat stroke. In Our Own Words Normally, your body

Heat Stroke

Clinical Definition Heat stroke is the most severe of three types of heat emergencies, also including heat cramps and heat exhaustion. Heat stroke can cause shock, brain damage, organ failure and death. Fever, irrational behavior and confusion are common. In Our Own Words Heat stroke is the most severe form of heat-related illness and can


Clinical Definition Hematuria, or blood in the urine, indicates that red blood cells are present. Even if you cannot see blood, you might have microscopic blood in your urine. Normally, the kidneys prevent blood from entering urine, but blood coming from the kidneys or other parts of the urinary tract (ureters, bladder, prostate, urethra) can


Clinical Definition Hemorrhoids are dilated vascular structures under the rectal mucosa. Hemorrhoids may develop outside of the external anal sphincter or inside the anal canal. They are often due to increased pressure on the anorectal area. Increased pressure may be due to constipation and straining during bowel movements. In Our Own Words Very common among


Clinical Definition A hernia is a bulge or protrusion of one organ or tissue through a wall or partition that normally contains it or holds it in. Hernias can develop in any number of locations in the human body, but often involve a portion of the gastrointestinal tract bulging through the abdominal/pelvic wall. In Our


Clinical Definition HIV, or human immunodeficiency virus, is a retrovirus that destroys the vital CD4 + T-cells of the immune system. Destruction of CD4 cells decreases immune system function and leaves patients susceptible to infections and disease. The infection can progress into acquired immunodeficiency syndrome (AIDS) if CD4+ T cells decrease to less than 200

Hodgkin Disease

Clinical Definition Hodgkin disease, or Hodgkin’s disease, is a malignant neoplasm of lymphoid cells and is one type of lymphoma. It differs from other lymphomas in that it produces abnormal Reed-Sternberg cells. It is characterized by enlargement of the lymph nodes, spleen and possibly liver. Hodgkin disease is divided into two main subtypes based on


Clinical Definition Homeopathic medicine is a system of alternative medicine based on the theory that utilizing potentiated substances, which in larger amounts would cause illness in healthy people, will allow or stimulate the body to heal itself. Homeopathic medicines are often made from plants and minerals and are used to treat a wide variety of

Human Papilloma Virus (HPV)

Clinical Definition Human papilloma virus (HPV) is a common infection caused by the papovaviridae family of viruses. There are many types of human papilloma viruses. More than 40 types of HPV are transmitted sexually and can affect the genitals. Genital HPV is associated with certain types of malignancies, including cervical neoplasia, laryngeal and anogential carcinomas.


Clinical Definition Hypertension is elevated pressure or tension on the arterial walls during systemic circulation. Increased force on the arterial walls can occur during the contractions of the myocardium, which is known as systolic pressure, and/or during rest, which is diastolic pressure. Although hypertension can be transient, a diagnosis of hypertension usually refers to a


Clinical Definition Hyperthyroidism is a endocrine-based condition that occurs when your level of thyroid hormones, T3 and T4, are above normal, and your thyroid-stimulating hormone (TSH) is low. In Our Own Words Located in the lower part of your neck, your thyroid gland produces hormones that regulate your body temperature and control your heart rate


Clinical Definition Hyperventilation is an increase in alveolar ventilation. It can lead to hypocapnia if carbon dioxide is removed from the blood in excess of production. Hyperventilation may be caused by physical or emotional stimuli. In Our Own Words Hyperventilation is increased breathing, which may lead to low levels of carbon dioxide in the body.


Clinical Definition Hypogammaglobulinemia is a decreased level of immunoglobulins (i.e., antibodies). Because of the decrease in disease-fighting immunoglobulins, hypogammaglobulinemia can cause an increased susceptibility to certain diseases and infections. Although its etiology is not always known, it may be present from birth or acquired later in life. In Our Own Words Hypogammaglobulinemia is a condition


Clinical Definition A hysterectomy is a surgical operation to remove the uterus and possibly other reproductive organs, such as the ovaries and/or fallopian tubes. In Our Own Words There are many reasons why women undergo a hysterectomy to remove the uterus, and possibly other reproductive organs. Medical reasons may include severe endometriosis and uterine fibroids,

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