Korean J Urol.  2012 Apr;53(4):268-274.

Influence of Overweight on 24-Hour Urine Chemistry Studies and Recurrent Urolithiasis in Children

• Chung JD
• Kim TH
• Myung SC
• Moon YT
• Kim KD
• Chang IH

Abstract

PURPOSE
We investigated the influence of overweight on 24-hour urine chemistry studies and recurrent urolithiasis (UL) in children.
MATERIALS AND METHODS
A retrospective cohort study was designed to assess children who presented with UL at a pediatric institution between 1985 and 2010. We calculated body mass index percentile (BMIp) adjusted for gender and age according to the 2007 Korean Children and Adolescents Growth Chart and stratified the children into 3 BMI categories: lower body weight (LBW, BMIp< or =10), normal BW (NBW, 10 or =85). Twenty-four hour urine chemistry studies (urine volume, creatinine, calcium, oxalate, citrate, and pH) were compared between the 3 BMIp groups. Univariate and multivariate analyses were performed to assess independent risk factors for stone recurrence.
RESULTS
A total of 125 patients were included. The age of the patients in the NBW group was older than that of patients in the LBW group, but 24-hour urine chemistry studies did not differ significantly between the three groups. Mean urine citrate levels were lower (0.273+/-0.218 mg/mg/d vs. 0.429+/-0.299 mg/mg/d, p<0.05) and the incidence of hypocitraturia was higher (81.5% vs. 45.7%, p<0.05)) in the recurrent stone former group. In the univariate analysis, hypocitraturia and acidic urinary pH were risk factors, but in the multivariate analysis, only hypocitraturia was a risk factor for stone recurrence (hazard ratio, 3.647; 95% confidence interval, 1.047 to 12.703). In the Kaplan-Meier curve, the hypocitraturia group showed higher recurrence than did the normocitraturia group (p<0.05).
CONCLUSIONS
Unlike in adults, in children, overweight adjusted for gender and age was not associated with 24-hour urine chemistry studies and was not a risk factor for recurrent UL. Hypocitraturia was the only risk factor for UL in children.

Keyword

Body mass index percentile; Overweight; Pediatric urolithiasis

MeSH Terms

Adolescent
Adult
Body Mass Index
Body Weight
Calcium
Child
Citric Acid
Cohort Studies
Creatinine
Growth Charts
Humans
Hydrogen-Ion Concentration
Incidence
Multivariate Analysis
Overweight
Recurrence
Retrospective Studies
Risk Factors
Urolithiasis
Calcium
Citric Acid
Creatinine

Figure

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  FIG. 1 Kaplan-Meier curve estimating the probability of stone recurrence according to patient age and body mass index percentile. LBW, lower body weight; NBW, normal body weight; UBW, upper body weight.

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