Hyperuricemia in Pediatric Renal Transplant Recipients

Prevalence and potential relevance of hyperuricemia in pediatric kidney transplant recipients-a CERTAIN registry analysis

BACKGROUND

Asymptomatic hyperuricemia is frequently observed in pediatric kidney transplant recipients; symptomatic hyperuricemia, however, is a rare complication. Only few data are available in this patient population. We, therefore, investigated the prevalence of hyperuricemia and its association with kidney transplant function and blood pressure in a multicenter cohort of pediatric kidney transplant recipients.

METHODS

This is a retrospective, observational multicenter registry study. All pediatric kidney transplant recipients in the CERTAIN database with at least one documented serum uric acid level and a follow-up of 5 years posttransplant were eligible. We identified 151 patients with 395 measurements of serum uric acid. We calculated the prevalence of hyperuricemia, analyzed potential risk factors and clinical consequences such as elevated blood pressure and reduced estimated glomerular filtration rate (eGFR). Statistical analysis was performed using IBM SPSS Statistics 26.

RESULTS

One hundred and ten of 395 (27.8%) serum uric acid levels were above 416 µmol/L (7.0 mg/dL), defined as the upper limit of normal. Univariate analysis showed a significant (p = .026) inverse association of serum uric acid with eGFR overtime. There was no significant association of serum uric acid concentrations with body mass index (z-score), blood pressure (z-score), or sex. No episodes of gout were documented.

CONCLUSION

This study shows that hyperuricemia is present in a considerable number of patients sometime after pediatric kidney transplantation and is associated with lower eGFR. Whether hyperuricemia contributes to faster decline of graft function or to the overall cardiovascular risk of these patients remains to be elucidated.

Switching from allopurinol to febuxostat: efficacy and safety in the treatment of hyperuricemia in renal transplant recipients

The aim of this study was to evaluate the efficacy and tolerability of febuxostat in renal transplant recipients who were previously treated with allopurinol (the daily oral dose is 100 mg). A 6-month cohort study was conducted with 46 renal transplant recipients who had hyperuricemia. In 22 patients, treatment was changed from allopurinol to febuxostat (febuxostat was given at an oral dose of 20 mg once a day), and the other 24 patients continued the allopurinol treatment (the daily oral dose is 100 mg). The serum levels of uric acid (UA), creatinine, other biochemical parameters, estimated glomerular filtration rate (eGFR), and adverse events were measured at baseline as well as at 1, 3, and 6 months after the switch to febuxostat. Serum UA levels significantly decreased from 470.82 ± 34.37 to 378.77 ± 51.97 μmol/L in the febuxostat group, and decreased from 469.46 ± 33.47 to 428.21 ± 23.37 μmol/L in the allopurinol group. The eGFR increased from 75.55 to 85.23 mL/min in the febuxostat group, and decreased from 78.79 to 70.31 mL/min in the allopurinol group. In renal transplant recipients, febuxostat reduced the serum UA levels resulting in minor short-term improvement of renal function with no changes in the other biochemical parameters.

Drug-induced hyperuricaemia and gout

Hyperuricaemia is a common clinical condition that can be defined as a serum uric acid level >6.8 mg/dl (404 µmol/l). Gout, a recognized complication of hyperuricaemia, is the most common inflammatory arthritis in adults. Drug-induced hyperuricaemia and gout present an emergent and increasingly prevalent problem in clinical practice. Diuretics are one of the most important causes of secondary hyperuricaemia. Drugs raise serum uric acid level by an increase of uric acid reabsorption and/or decrease in uric acid secretion. Several drugs may also increase uric acid production. In this review, drugs leading to hyperuricaemia are summarized with regard to their mechanism of action and clinical significance. Increased awareness of drugs that can induce hyperuricaemia and gout, and monitoring and prevention are key elements for reducing the morbidity related to drug-induced hyperuricaemia and gout.

Osteonecrosis with renal damage in HIV patients undergoing HAART

Rheumatoid arthritis in HIV patients undergoing HAART is associated with increased risk of side effect. Elevation of uric acid (UA) is important in tissue damage, deposition of crystal in joints leads to the development of rheumatoid arthritis in the HAART complaint group. This study was carried out to investigate the relationship of uric acid, RA factor, ANA, ESR, cystatin C, urea and creatinine in the HAART complaint group. Moreover; the ratio of uric acid/cystatin C, uric acid/urea and uric acid/creatinine were also studied. To analyze the progression of HIV, the immunological parameters were correlated with uric acid. Our result showed a statistically high significant increase in uric acid, RA factor, ANA, ESR, cystatin C, urea and creatinine in the HAART complaint group when compared to HAART non-complaint group, early stage and control. The ratio of uric acid/cystatin C, uric acid/urea, uric acid/creatinine were significantly increased in the HAART complaint group. Statistically significant positive correlation was observed between uric acid and cystatin C, urea, creatinine, absolute CD4 and CD8 count. The increased level of uric acid, RA factor, ANA, ESR, cystatin C and increased ratio of uric acid/cystatin C in the HAART complaint group might conclude the mechanism underlying the increased risk for rheumatoid arthritis in the HAART complaint group which may relate to the combined effects of low-grade inflammation and renal dysfunction.

Metabolic risk factors and long-term graft function after paediatric renal transplantation

The aim of this study was to evaluate metabolic risk factors and their impact on long-term allograft function in paediatric renal transplant (RTx) patients. We reviewed the medical records of 210 RTx patients who underwent transplantation at a median age of 4.5 years (range 0.7-18.2) and a median follow-up of 7.0 years (range 1.5-18.0). Data on lipid and glucose metabolism, uric acid levels, weight and blood pressure were collected up to 13 years post-RTx, and the findings were correlated with the measured glomerular filtration rate (GFR). Beyond the first year, GFR showed gradual deterioration with a mean decline of 2.4 ml/min/1.73 m(2)/year. Metabolic syndrome, overweight, hypertension and type 2 diabetes were diagnosed in 14-19%, 20-23%, 62-87% and 3-5% of the patients, respectively. These entities showed only mild association with the concomitant or long-term GFR values. Dyslipidaemia was common and hypertriglyceridaemia associated with a lower GFR at 1.5 and 5 years post-RTx (P = 0.008 and P = 0.017, respectively). Similarly, hyperuricaemia was frequent and associated significantly with GFR (P < 0.001). Except for hyperuricaemia and hypertriglyceridaemia, metabolic risk factors beyond the first postoperative year associated modestly with the long-term kidney graft function in paediatric RTx patients.