Clinical Presentation of Chronic ITP
Definition. Chronic means that the disorder persists unless treated and ITP stands for: I-immune; T-thrombocytopenic; P-purpura. Immune means that the body's immune system is involved in destroying platelets or damaging megakaryocytes; thrombocytopenia means a low platelet count and purpura is a medical name for bruising.
In chronic ITP, the body's immune system (for reasons that are not known) produces autoantibodies and specific cytotoxic T lymphocytes which cause platelet destruction and possibly damage megakaryocytes, resulting in decreased platelet production. A similar clinical pattern may occur with certain drugs (e.g., quinidine, quinine, or sulfa-like drugs, although many drugs have been involved) and may be associated with other diseases such as systemic lupus erythematosus, lymphoproliferative disorders (e.g., non-Hodgkin's lymphoma) or infection (e.g., HIV infection, cytomegalovirus infection or hepatitis). These other causes must be ruled out before the diagnosis of chronic ITP can be made.
Clinical findings. Patients may have no symptoms and the low platelet count may be noted during routine blood studies. However, most patients see their doctor because they develop a skin rash on their legs (called petechiae, a collection of small pinpoint bruises), excessive bruising or, less commonly, bleeding from the nose, gums or rarely from the gastrointestinal tract (stomach or bowel) or genitourinary tract (blood in the urine). Women may note prolonged or heavy menstrual bleeding. Symptoms may be exagerrated by certain medications which interfere with platelet function (e.g., aspirin, ibuprofen).
Laboratory findings. The blood count is normal except for a low platelet count (a normal platelet count in our laboratory is 130,000 to 400,000). Occasionally, patients are anemic if significant bleeding has occurred. Bone marrow examination is normal except that the number megakaryocytes (the cells which produce platelets) is often increased since the body is attempting to respond to the destruction of platelets by increasing their production. Autoantibodies against platelets can be detected in most patients. In chronic ITP, all other laboratory tests should be normal (including tests to rule out HIV, hepatitis or cytomegalovirus infection) .
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