Does obesity or hyperuricemia influence lithogenic risk profile in children with urolithiasis?

Abstract

BackgroundThere are indications that obesity and hyperuricemia may influence the formation and composition of urinary stones. The aim of our study was to determine the effect of obesity and hyperuricemia on the urinary lithogenic risk profile in a large cohort of pediatric patients.MethodsThe study population comprised 478 children with urolithiasis and 517 healthy children (reference group). We studied the effects of obesity on the lithogenic profile by dividing the patients with urolithiasis into two groups based on body mass index Z-score (patients who were overweight/obese vs. those with normal weight for age) and comparing the two groups. To study the effect of hyperuricemia on the lithogenic profile, we divided the patients with urolithiasis into two groups based on the presence or not of hyperuricemia (110 patients with urolithiasis accompanied by hyperuricemia vs. 368 patients with urolithiasis and normal serum uric acid levels) and compared the groups.ResultsAmong the children and adolescents with urolithiasis and hyperuricemia, there was a significantly lower excretion of crystallization inhibitors (citrates, magnesium). We also found significantly negative correlations between serum uric acid levels and the urine citrate/creatinine ratio (citrate/cr.; r = −0.30, p < 0.01), as well as the magnesium/cr. ratio (Mg/cr.; r = −0.33, p < 0.01). There was no statistically significant differences in the urinary excretion of oxalates, citrates, calcium, phosphorus, magnesium and uric acid between children with urolithiasis who were either overweight or obese and children with urolithiasis who had a normal body weight.ConclusionsIn our pediatric patient cohort, hyperuricemia was associated with a decrease in the excretion of crystallization inhibitors in the urine, but the clinical relevance of this observation needs to be confirmed in future studies. Obesity and overweight had no direct influence on the lithogenic risk profile in the urinary stone formers in our study, but there was an indication that higher serum uric acid may be associated with impairment in renal function, which in turn could influence the excretion of lithogenic parameters.

GWAS of clinically defined gout and subtypes identifies multiple susceptibility loci that include urate transporter genes

“…Nevertheless, recent studies have revealed associations between hyperuricaemia and magnesium intake, 29 serum magnesium level 30 and magnesium excretion. 31 Together with previous reports, our findings support the hypothesis that there could be some relationship between gout and magnesium handling via magnesium transporters including NIPAL1, and that the present study could well provide new insights into the genetic background of urate and magnesium handling in patients with gout/hyperuricaemia. FAM35A is ubiquitously expressed in organs including the kidney, and our immunohistochemical analysis of human kidney also revealed cytosolic immunoreactivity of the FAM35A protein mainly in the distal tubules (figure 4B).…”

Biochemical diagnosis in 3040 kidney stone formers in Argentina

“…Hyperuricemia alone is not considered a cause of nephrolithiasis, but higher serum uric acid may be associated with impairment in renal function, which in turn could influence the excretion of lithogenic parameters [54] and indirectly can cause insulin resistance leading to a reduced ammonium production and transport, which lowers urine pH and enhances renal stone formation [55,56].…”

24 Hour urine metabolic differences between solitary and multiple stone formers: Results of the Collaboration on Urolithiasis in Pediatrics (CUP) working group

“…Eisner et al found that as BMI increased, urine oxalate excretion decreased and super-saturation of calcium phosphate increased [18]. Other recent studies support that there may be no substantial metabolic differences between healthy non-obese and obese stone formers [19][20][21]. In contrast, another retrospective study found that overweight and obese stone forming children were more likely to have decreased levels of urine citrate, phosphate, and magnesium and increased hypercalcuria when compared with patients with normal BMI [22].…”