Renal handling of uric acid under cyclosporin A treatment

The renal handling of uric acid during cyclosporin A (CyA) treatment was investigated by clearance studies using 24-h urine collections in 28 paediatric renal transplant recipients (CyA group), and the results were compared with those of 19 renal transplanted children treated with azathioprine and prednisolone (AZA group), 35 children with chronic renal failure (CRF) and 10 children with normal renal function (N group). Serum uric acid levels were significantly higher in the CyA group (567±156 mol/l) compared with the AZA group (378±98), the CRF group (415±119) and the N group (290±68). Mean uric acid clearances in each group measured 3.9±2.8 ml/min per 1.73 m² (CyA), 5.6±3.4 (AZA), 4.0±2.2 (CRF) and 8.4±3.7 (N). Calculation of the net tubular uric acid reabsorption per millilitre glomerular filtration rate revealed a significantly increased value of 0.53±0.15 mol/ml in the CyA group (P<0.01) compared with 0.34±0.08, 0.29±0.15 and 0.27±0.07 mol/l for the AZA, CRF and N groups respectively. We therefore conclude that CyA treatment is associated with an increased net tubular reabsorption of uric acid, which may lead to hyperuricaemia.