Microangiopathic hemolytic anemia complicating FK506 (tacrolimus) therapy

We describe 3 episodes of microangiopathic hemolytic anemia (MAHA) in 2 solid organ recipients under FK506 (tacrolimus) therapy. In both cases, discontinuation of FK506 and treatment with plasma exchange, fresh frozen plasma replacement, corticosteroids, aspirin, and dipyridamole led to resolution of MAHA. In one patient, reintroduction of FK506 led to rapid recurrence of MAHA. FK506-associated MAHA is probably rare but physicians must be aware of this severe complication. In our experience and according to the literature, FK506 does not seem to cross-react with cyclosporin A (CyA), an immuno-suppressive drug already known to induce MAHA.