Post-transplant erythrocytosis and immunosuppression with cyclosporin: a case-control study

Review of 142 renal transplant recipients treated with cyclosporin and prednisolone revealed 23 patients with post-transplant erythrocytosis. The clinical characteristics of these patients were compared with 23 cyclosporin/prednisolone-treated control subjects matched for age, sex, and duration of transplant. Erythrocytosis developed between 6 weeks and 30 months (median 12 months) after transplant. It persisted in 16 patients and resolved spontaneously in five. In two patients the decrease in haematocrit was associated with acute leukaemia in one and sudden deterioration of renal function in the other. In the study group there were fewer HLA (A, B and DR) mismatches (P less than 0.05) and greater pretransplant haematocrit (P less than 0.01) than in the control group. Other clinical factors--previous allografts, panel reactive cytotoxic antibodies, duration and type of dialysis, transplant function, pre- and post-transplant blood pressure, number of rejection episodes, cyclosporin concentration and dose, smoking habits and use of diuretics--did not differ significantly between the two groups. In our experience, erythrocytosis in cyclosporin-treated patients is a relatively common phenomenon and does not, in general, resolve spontaneously. It is unrelated to transplant function or rejection episodes but affects patients with well-matched kidneys and elevated pretransplant haematocrit values.