Thrombocytopenia describes an extreme shortage of platelets in the blood. Although the average platelet count in a healthy human being is about 300,000 per microlitre, there is a large amount of individual variation and 95% of human beings have a count from 150,000 to 450,000. For a patient to be described with thrombocytopenia, they must have a platelet count of less than 50,000.

A person exhibiting thrombocytopenia may not in fact be suffering from any disease at all (in rare individuals, the platelet count can normally be this low). A patient may even be asymptomatic and the condition will only show up in routine blood tests. However, it can exhibit as bruising, pupura, petechia, nosebleeds or bleeding gums.

Many diseases present with thrombocytopenia.Vitamin B-12 deficiency, folate deficiency, leukemia, liver failure, sepsis, infection, Dengue fever and several genetic conditions present with thrombocytopenia because fewer platelets are created. Thrombotic thrombocytopenic purpura, Lupus and AIDS can present with it due to increased destruction of platelets. Methotrexate, interferon and other medications can also cause thrombocytopenia.

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