Reduced levels of blood cells called platelets, causing bleeding into the skin and internal organs
Thrombocytopenia is the medical term for a reduction in the number of platelets in the blood circulation. Platelets are small blood cells, made in the bone marrow, that play a vital part in blood clotting, and a reduction in their numbers leads to a tendency to excessive bleeding.
Thrombocytopenia may be caused either by a failure of the bone marrow to produce platelets or by excessive destruction of platelets in the spleen. Platelet production in the bone marrow may be reduced by disorders such as leukaemia or aplastic anaemia or by chemotherapy. An excessive destruction of platelets is usually due to an abnormal immune reaction in which the body produces antibodies that attack platelets (immune thrombocytopenia). The cause is often unknown, but it may be triggered by blood transfusions or by drugs such as quinine (see Antimalarial drugs) and rifampicin (see Antituberculous drugs). In children, the condition is often triggered by a viral infection.
Thrombocytopenia may occur as a result of infection, such as HIV (see HIV infection and AIDS), or an autoimmune disorder such as systemic lupus erythematosus. In some cases, it is associated with cancer.
The symptoms of thrombocytopenia are often mild and may include:
A rash of many tiny red dots or large purple patches, neither of which fade when pressed (see Purpura).
Bleeding gums and heavy nosebleeds.
In women, heavy menstrual bleeding.
If you have very low levels of platelets, you may be at increased risk of stroke due to bleeding in the brain.
If your doctor suspects from your symptoms that you have thrombocytopenia, he or she may arrange for you to have a blood test to measure your platelet levels. Your doctor may also arrange for you to have a bone marrow aspiration and biopsy in order to obtain tissue samples for examination under the microscope.
Mild thrombocytopenia triggered by a viral infection often clears up without treatment. Bleeding due to extremely low platelet levels may be treated with intravenous platelet infusions while the cause is investigated. If you have drug-induced thrombocytopenia, you will be prescribed an alternative drug that does not affect platelets; the level of platelets in the blood should promptly return to normal. When the condition is due to an immune disorder (immune thrombocytopenia), an oral corticosteroid may be prescribed. In severe or recurrent cases due to increased destruction of platelets, removal of the spleen may be necessary for a lasting cure.
From the 2010 revision of the Complete Home Medical Guide © Dorling Kindersley Limited.