Repeat blood donors make up a significant proportion of the blood donor pool in the United States. Recent studies have found that frequent blood donation increases the risk for iron deficiency, which may be associated with abnormal platelet counts. Researchers at the National Institute of Health retrospectively examined platelet levels among 1273 hemoglobin (Hb)-deferred whole blood donors. Fifty-five percent (619/1128) of female and 70% (102/145) of male Hb-deferred donors had iron deficiency based on serum ferritin cut-off values of 20 µg/L and 30 µg/L, respectively. On average, iron-deficient donors had higher platelet levels than donors with a normal range of iron, but only 4.4% (32/721) had thrombocytosis (>400,000 platelet/µL). Thrombocytopenia (<150,000 platelets/µL) was also observed but was not significantly different in donors with low and normal levels of iron (1% vs. 2%, respectively). Based on 291 of 1273 donors who took oral iron tablets for at least 7 days, iron-replacement decreased platelet counts in female and male donors on average by approximately 20,000 platelets/µL. Iron replacement did not affect platelet count in donors with normal iron levels. Both iron deficiency and platelet counts should be monitored among repeat blood donors.
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