The mother of a child with idiopathic thrombocytopenic purpura is very worried about whether her child will develop serious bleeding. When reassuring this mother, it might be helpful if the physician informs her that the threshold for generalized bleeding is about how many platelets/mm3?
Normal platelet counts are in the 150,000-450,000/mm3 range. It is useful to know that peripheral blood platelet counts less than about 15,000-20,000/mm3 are required before generalized bleeding usually occurs. Few physicians choose to actively treat patients who are not currently bleeding and whose platelet counts are greater than 100,000/mm3. Clearly, patients with counts less than 15,000/mm3 probably require active therapy, possibly with platelet transfusions. However, there is more disagreement about how to handle patients with counts in the 20,000-50,000/mm3 range, and you may encounter some physicians who will attempt to transfuse these patients. (However, this practice is no longer recommended by the American Blood Bank Association unless the patients is actively bleeding.) Idiopathic thrombocytopenic purpura is due to an autoimmune attack on the platelets, leading to their clearing by the spleen. Splenectomy may be helpful in refractory cases. A count of 5,000 platelets/mm3 dangerously low, and platelet transfusion should have been considered earlier. Some physicians will give platelet transfusions for actively bleeding patients with counts of 50,000/mm3. Platelet counts of 100,000/mm3 do not usually require platelet transfusion, even when bleeding. Ref: Diz-Kucukkaya R., Chen J., Geddis A., Lopez J.A. (2010). Chapter 119. Thrombocytopenia. In J.T. Prchal, K. Kaushansky, M.A. Lichtman, T.J. Kipps, U. Seligsohn (Eds), Williams Hematology, 8e.
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