Azathioprine-induced pure red-cell aplasia.

Long-term administration of azathioprine is widely used to prevent rejection in organ transplantation and in the treatment of autoimmune diseases. Bone marrow toxicity is a well-known side-effect of azathioprine. Macrocytosis, with or without megaloblastic erythropoiesis in the bone marrow, and (mild) leukopenia are frequently seen [1-4]. Less common effects are anaemia, thrombocytopenia and pancytopenia [5,6]. Pure red-cell aplasia is a rare complication of azathioprine, which was first reported in two patients by McGrath et al. in 1975 [1]. So far, no more than 10 cases have been reported in the literature [1,2,7-12]. We describe this disorder in a renal transplant patient. Discontinuation of the drug resulted in full recovery.