Hyperuricemia and gout following pediatric renal transplantation

Hyperuricemia and gout are common complications in adult renal transplant recipients. In pediatric recipients, however, hyperuricemia seems to be rare, but data are scarce. Thirty-two children (21 males, 11 females) were investigated for a median time of 4.8 years (range: 0.4–11.2 years) following renal transplantation. The median age of this pediatric study group was 13.9 years (range: 5.7–20.3 years), and the calculated glomerular filtration rate (GFR) was 61 ml/min per 1.73 m² (range:12–88 ml/min per 1.73 m²). All patients were given calcineurin inhibitors, with 22 and ten children receiving cyclosporine A (CSA) and tacrolimus (TAC), respectively. The median plasma uric acid was 385 μmol/l (range: 62–929 μmol/l); 15 children (47%) were above the age-related normal range. Only one patient experienced gouty arthritis. There was a significant correlation between plasma uric acid concentration and both time span after transplantation and plasma creatinine, and an inverse correlation to GFR (p<0.05). No significant correlation was found between plasma uric acid and body mass index (BMI). Plasma uric acid concentrations were neither different among CSA- and TAC-treated children, nor did they correlate with drug exposure or blood trough levels of CSA or TAC. Plasma uric acid concentration was not different when compared to children with chronic renal failure (CRF) of a similar degree in native kidneys. We conclude that hyperuricemia is common among pediatric renal transplant recipients and rather a consequence of chronic renal transplant dysfunction than the use of calcineurin inhibitors. Gout, however, is rare.