Thrombocytopenia is the medical term that refers to a low or reduced platelet count. Platelets are cells in the blood that allow blood to clot and prevent the loss of red blood cells, which carry oxygen throughout the body. Platelets are lost even in healthy bodies during normal bodily functions, but are replaced with new platelets produced in the bone marrow. Thrombocytopenia occurs when platelets are not replaced at the same rate as loss or when abnormal platelet destruction occurs.
Thrombocytopenia can cause abnormal bleeding, especially from the nose and in the stomach and intestines. Signs of thrombocytopenia may include nosebleeds, unexplained vaginal bleeding, or vomiting blood. Thrombocytopenia can be diagnosed through routine blood tests and a complete blood count, which also measures the levels of red and white blood cells. In some cases, it may also be necessary to analyze the bone marrow. During a physical exam, the spleen may also be checked to see if it is enlarged.
Causes of thrombocytopenia can include diseases, infections, and medications. Thrombocytopenia can originate in the bone marrow, in the bloodstream, or outside the bloodstream. Thrombocytopenia is usually the result of chemotherapy and radiation, and occasionally affects patients taking heparin. A low platelet count does not necessarily indicate disease and is sometimes secondary to another condition.
When the bone marrow makes platelets at a normal rate, but the platelet count is low in the bloodstream, this is often the result of an infection destroying platelets faster than they are being made. This condition is known as idiopathic thrombocytopenic purpura (ITP).
Thrombocytopenia caused by reduced production in the bone marrow is more serious than platelet destruction as in ITP. However, any sign of thrombocytopenia, including unexplained bleeding from the nose, gums, or lower legs, or the appearance of blood in vomit or stool, should be reported to a doctor. People with thrombocytopenia are at high risk for abnormal or serious bleeding, including internal bleeding. Treatment for thrombocytopenia depends on the cause but may include steroids or other medications and may require platelet transfusions.