The platelet count measures the number of small cell fragments in blood that form the first plug at a site of injury. It speaks for the clotting side of the blood and for the marrow's production of megakaryocytes, and it is part of every complete blood count.
No readings for this marker yet.
Raised counts most often follow inflammation, infection, iron deficiency, recent surgery or removal of the spleen, and less often reflect a marrow disorder of production. Lowered counts most often accompany viral infection, alcohol use, enlarged spleen, autoimmune destruction, some medications, or reduced marrow output. Counts are also watched during treatment with drugs such as acetylsalicylic acid, clopidogrel, warfarin, valproic acid and methotrexate; either direction, and especially easy bruising or bleeding, belongs in a conversation with a doctor.
Platelets clump in the EDTA tube in some people, which produces a falsely low count that a blood film or a repeat in a different tube resolves; counts also rise briefly after exercise and fall in pregnancy. The result is read with mean platelet volume, which indicates whether circulating platelets are young and large, and with hemoglobin and the white cell count to see whether one line or the whole marrow is affected.
Reference ranges are general adult values and depend on lab, assay, age and sex. For orientation, not diagnosis — discuss results with your doctor.