5 YEARS FOLLOW-UP OF RENAL GLOMERULAR AND TUBULAR FUNCTIONS IN HEART-TRANSPLANT RECIPIENTS

Background: Many studies have shown that cyclosporine A may have detri mental long-term effects on kidney function. However, few prospective long-term studies have assessed both glomerular and tubular functions of the kidneys in heart transplant recipients. Methods: We examined 10 heart transplant recipients prospectively for 5 years. Hemodynamic da ta were obtained by standard heart catheterization technique, and glom erular filtration rate and blood flow were calculated as clearance of inulin and paraaminohippuran, respectively. Tubular functions were ass essed by renal excretion of enzymes and albumin and by the lithium cle arance method. All patients received cyclosporine A, azathioprine, and prednisolone as immunosuppressive regimen. The dose of cyclosporine a veraged 3.9 +/- 0.3 during the first year and 3.2 +/- 0.3 mg/kg up to 5 years. Results: All patients completed the study. Four received reje ction therapy. Six were treated for hypertension. Cardiac output remai ned unchanged and averaged 5.5 +/- 0.9 L/min at baseline. No change wa s found in any of the measured or calculated central hemodynamic param eters except a tendency toward an increased systemic peripheral resist ance with time. Glomerular filtration remained constant at 66 +/- 22 m l/min, renal plasma flow showed a tendency to decline averaging 361 +/ - 133 at baseline and 254 +/- 68 ml/min at 5 years (p = 0.08). Albumin excretion rate increased from 22 +/- 27 to the 102 +/- 100 mu g/min b etween 1 and 5 years (p < 0.05). The excretion of tubular enzymes, N-a cetyl-6-glucosaminidase and alkaline phosphatase, and the renal handli ng of lithium remained unchanged. Conclusions: Cyclosporine therapy ov er 5 years did not progressively impair glomerular or tubular function s. However, the occurrence of microalbuminuria may be caused by therap y with cyclosporine itself or associated hypertension.