Frequency of leukopenia incidents following azathioprine therapy after kidney transplantation.

The frequency of leukopenia incidents and its dependence on the dose of azathioprine and kidney function were analyzed in 149 patients during the first 3 months after kidney transplantation. The results were compared with the data of 42 transplantation centers of the world. We found that the frequency of leukopenia increases significantly following azathioprine dosage exceeding 1.99 mg/kg body weight/day. The toxicity of the drug depends on the kidney function. Most of the leukopenia incidents were detected during the first 5 weeks after kidney transplantation. In 70% of the cases a first leukopenia incident is followed by a second. Low azathioprine dosage after the first episode diminishes the number of second incidents.