- Anemia (hemoglobin (Hb) less than 11 gm/dl) or thrombocytopenia (platelets less than 100,000 per ml). However, potential donors with Hb levels less than 11 gm/dl that is due to iron deficiency will be eligible as long as the donor is initiated on iron replacement therapy and the case is individually approved by NIH Department of Transfusion Medicine (DTM).