Thrombocytopenia associated with repletion of iron in iron-deficiency anemia.

Two patients with iron deficiency experienced rapid decreases in their platelet levels following initiation of replacement therapy with oral ferrous sulfate or ferrous gluconate. The first patient, whose pretreatment platelet count was 168,000 per mm3, developed marked thrombocytopenia (platelet count, 21,000 per mm3) on the sixth day of iron repletion. The second patient's platelet level fell from 725,000 to 105,000 per mm3 on the tenth day of therapy. In both instances, platelet levels gradually returned to normal levels. The data suggest that the administration of oral iron resulted in an acute reduction in platelet production. The mechanism(s), prevalence, and clinical significance of thrombocytopenia following iron repletion in patients with iron deficiency anemia remain unknown.