Implications for kidney disease in obese children and adolescents

Abstract

Increasing attention has been focused on the implications of obesity in adults on the development of kidney disease, but data on the obese pediatric population are lacking. The aim of this study was to investigate whether changes in various renal function indexes/markers, as expressed by the glomerular filtration rate [GFR, as estimated by the Schwartz formula (eGFR)], serum cystatin C (CysC) level, albumin excretion rate (AER), and modifications in nitric oxide (NO; an important modulator of renal function and morphology), urinary isoprostanes (markers of oxidative stress), and blood pressure (BP), can be detected in obese children and adolescents when compared to normal weight controls. Blood and urinary samples were collected to evaluate markers of renal function, serum and urinary NO, and urinary isoprostanes in 107 obese Caucasian subjects and 50 controls. Ambulatory BP monitoring (ABPM) was performed in all cases. Obesity was expressed by the body mass index standard deviation score (SDS-BMI), and insulin resistance by the homeostasis model assessment of insulin resistance (HOMA-IR). CysC and eGFR did not significantly differ between the two groups; AER was increased in obese children. CysC and GFR were related to HOMA-IR, and AER was related to HOMA-IR and SDS-BMI. Obese subjects had reduced NO levels and increased urinary isoprostanes and BP measurements; all three parameters were related to SDS-BMI and insulin resistance. ABPM showed an increased incidence of hypertension and non-dipping in the obese group. Based on our comparison of obese and nonobese children, we conclude that renal involvement is not an early clinically evident manifestation of adiposity in childhood, since no overt changes in eGFR and only a mild albuminuria were detected. A longer exposure to obesity is probably needed before renal function impairment appears.

Deteriorated glucose metabolism with a high-protein, low-carbohydrate diet in db mice, an animal model of type 2 diabetes, might be caused by insufficient insulin secretion

“…Our results also indicate that a high-protein diet increased urinary albumin in both CT and db mice, which is inconsistent with our previous report regarding db mice under long-term conditions [12]. Although further experiments are needed to determine the direct effect of dietary protein on renal manifestations, this discrepancy may be explained by the presence or absence of BW change, as BW has been associated with urinary albumin concentration [22]. However, our current study utilized short-term experiments in which we observed no significant BW change; therefore, the effects of a high-protein diet may be more clearly reflected in urinary albumin excretion levels.…”

Urinary Netrin-1: A New Biomarker for the Early Diagnosis of Renal Damage in Obese Children

“…Our study revealed that obese patients had higher urinary NAG and KIM-1 values compared to controls, but that there was no difference in urinary NGAL (22). In another study, it was demonstrated that obese children and adolescents had reduced nitric oxide (NO) levels and increased urinary isoprostanes when compared to normal weight controls (23). We found that urinary netrin-1 is significantly elevated in obese patients without microalbuminuria when compared to controls.…”

The Glomerular Filtration Rate and Proteinuria in Obese Children

“…Some researchers reported high GFR values in obese patients (34,36), whereas others reported low GFR values (26,38). Because of difficulty in collecting 24-hour urine in children, 24-hour creatinine clearance results were rarely reported (28).…”