Serum uric acid concentration is associated with lower glomerular filtration rate in children undergoing kidney transplantation.

BACKGROUND: The relationship between serum concentration of uric acid (UA) and chronic kidney disease is complex due to many confounding variables. There is currently debate over whether hyperuricemia acts as a marker of kidney disease or as an independent risk factor. OBJECTIVES: To test the impact of serum UA concentration on the estimated glomerular filtration rate (GFR) of children undergoing kidney transplantation. PATIENTS AND METHODS: Prospective longitudinal study of children and adolescents after kidney transplantation. We analyzed clinical, anthropometric, and laboratory data at pre-transplant and 1, 3, and 6 months after transplant. We developed models of repeated measures analysis, using the generalized estimating equations technique for the outcome evolution of the estimated GFR at 1, 3 and 6 months. High serum UA concentration at 1 and 3 months was modeled as the main exposure variable. RESULTS: We included 103 transplant patients. In a model adjusted for time, recipient sex and age, the occurrence of acute rejection episodes, and the estimated glomerular filtration at baseline, the trajectory of GFR exhibited an inverse relationship with UA (ß = -7.1, 95% CI: -11.5 to -2.6, p < .01). CONCLUSION: Serum UA increase was associated with lower graft function over time.

Abdominal circumference measurement by ultrasound does not enhance estimating the association of visceral fat with cardiovascular risk.

OBJECTIVES: To evaluate the association between visceral fat and cardiovascular risk factors and to compare the ultrasonographic measurements of abdominal visceral fat with abdominal circumference (AC). METHODS: This observational cross-sectional study categorized pubertal and postpubertal adolescents into a control group (n = 49) and an obese group (n = 46). Weight, height, AC, blood pressure, biochemical tests (lipid profile, triacylglycerols, fasting glucose for insulinemia, and serum uric acid), and ultrasound to measure visceral fat were assessed. RESULTS: We found significant differences in the vascular risk variables between the groups, except for total cholesterol and fasting blood glucose level. We also observed that 31 subjects in the control group presented abnormalities in cardiovascular risk factors. The correlations between abdominal visceral fat (measured by ultrasound or the AC) and cardiovascular risk factors were significant. In the entire sample, AC presented better sensitivity and specificity than the ultrasound-measured abdominal visceral fat for identifying the presence of a cluster of at least three cardiovascular risk factors (areas under the receiver operating characteristics curve 0.87 and 0.73, respectively). CONCLUSION: Ultrasonographic measurements of visceral fat were correlated with cardiovascular risk factors, but this association was also demonstrable with AC measurements. Our results suggest that the measurement of visceral fat by ultrasound is unnecessary for the diagnosis of cardiovascular risk in well-nourished or obese adolescents.