Bone marrow function during quadruple immunosuppressive therapy after renal transplantation

Bone marrow function was evaluated in 50 patients treated with quadruple immunotherapy (prednisone, azathioprine, anti-lymphocyte globulin [ALG] until creatine clearance > 10 ml/min, cyclosporine thereafter) after renal transplantation. Thrombocytopenia (< 100 mio./ml) developed in 30% of patients and leucopenia in 4%. Leucopenia was always accompanied by thrombocytopenia. Thrombocytopenia usually developed within 3 days of the operation. The most significant factors in the development of thrombocytopenia were ALG treatment and a low platelet count (< 250 mio./ml) on admission. The toxic effect of ALG was immediate, but disappeared within 5 days of ALG discontinuation. Other factors of importance were female sex, low weight (< 70 kg) and long (> 1 year) dialysis duration. Cyclosporine had no toxic effect. Azathioprine treatment played only a minor role in the development of thrombocytopenia but patients with low (100-200 mio./ml) and falling platelet counts who later develop thrombocytopenia were treated with significantly (p < 0.01) higher azathioprine dosages. The present study suggests that thrombocytopenia incidence can be reduced if azathioprine treatment is reduced to 1 mg/kg/day under the following circumstances: 1) small female patients; 2) platelet count < 250 mio./ml on admission; 3) platelet count < 200 during admission and falling. ALG treatment should usually be limited to 14 days, but azathioprine dosage can safely be increased after ALG discontinuation.