Effect of cyclosporin on lung diffusing capacity in renal transplant patients

A prospective lung function study pre- and postrenal transplantation was performed on 21 patients in order to evaluate whether cyclosporin decreased the lung diffusing capacity due to lung toxicity. Initial inclusion criteria were absence of respiratory symptoms and normal findings in both chest X-ray and pulmonary function tests. Participants had to be nonsmokers. We determined spirometry including lung volumes, arterial blood gases, carbon monoxide diffusing capacity by the single breath method (DLCOSB), and rate of CO uptake per unit of lung volume (KCO) before and 3, 6, and 12 months after transplantation. Immunosuppression consisted of prednisone and cyclosporin, maintaining total blood levels between 100 and 250 ng/ml. Spirometric and blood gases data remained within reference levels during the follow-up. Hemoglobin (Hb) pretransplant concentrations remained low, returning to their normal levels post-transplantation. Pretransplant DLCOSB levels were slightly decreased but fell within the therapeutic range after correction for Hb concentration, unlike the mean KCO levels which remained slightly diminished despite their correction. In post-transplant controls, the values obtained for both DLCOSB and KCO were significantly higher at the different post-transplant intervals (P < 0.005) than pretransplantation but only when compared without Hb correction. No significant differences for DLCOSB were found when corrected values were compared, and an improvement in the KCO appeared to be significant at 12 months posttransplantation. Based on these findings, we feel that when serum levels are within the therapeutic range, cyclosporin fails to alter the respiratory function or the pulmonary diffusing capacity of the lung.