Hyperuricemia and gout following pediatric renal transplantation

Abstract

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 m(2) (range:12-88 ml/min per 1.73 m(2)). 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 micromol/l (range: 62-929 micromol/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.

Hyperuricemia in Pediatric Renal Transplant Recipients

“…15 In 1 study with 32 pediatric renal transplant recipients, the prevalence of hyperuricemia was reported as being 47%; the authors did not find any difference of hyperuricemia rate according to different calcineurin inhibitors. 8 In this study, our group was larger, and we found that 39% of patients on cyclosporine and 16% of patients on tacrolimus had hyperuricemia. The rate of hyperuricemia was greater in those patients receiving cyclosporine; however, the patients on cyclosporine had lower estimated glomerular filtration rates and longer transplant durations compared with the patients receiving tacrolimus.…”

“…9 Estimated glomerular filtration rate was calculated according to the Schwartz formula with cystatin C. 10 The upper limits of serum UA levels were regarded as 352, 339, and 416 μmol/L in children aged 2 to 15 years in both sexes. 8 The blood pressure of each patient was measured at each follow-up visit. Hypertension was defined as the average systolic blood pressure or diastolic blood pressure ≥ 95th percentile for sex, age, and height on at least 3 separate occasions.…”

“…Edvardsson and associates 7 also have described hyperuricemia in 23% of pediatric renal transplant recipients on CsA treatment 30 months after a renal transplant. Sparta and associates 8 have described hyperuricemia in 47% of 32 pediatric renal transplant recipients.…”

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“…1,2 In most studies, serum uric acid level was a marker of renal dysfunction. [2][3][4][5][6] However, hyperuricemia occurs early after transplant and is associated with use of diuretics, cyclosporine therapy, a history of hyperuricemia, and decreased glomerular filtration rate (GFR).…”

“…1,2 In most studies, serum uric acid level was a marker of renal dysfunction. [2][3][4][5][6] However, hyperuricemia occurs early after transplant and is associated with use of diuretics, cyclosporine therapy, a history of hyperuricemia, and decreased glomerular filtration rate (GFR). 1,3,5,7,8 The effect of hyperuricemia after kidney transplant on graft outcome has not been fully established, but a small number of studies have suggested that an increased serum uric acid level is a prognostic factor for the development of renal allograft impairment.…”