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

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 =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.

Measurement of Necrotic Portion in Legg-Clave-Perthes Disease: Comparison of MRI Volume Measurement Method andCatterall Classification

PURPOSE: The purpose of this study was to evaluate the extent of necrosis of the femoral head inLegg-Clave-Perthes (LCP) disease. This involved the use of MRI, followed by volume measurement and the use of theCatterall classification system; the difference between the grade obtained using each of these approaches was thendetermined. MATERIALS AND METHODS: We retrospectively reviewed 28 hip-joint MR images on which a diagnosis of LCPdisease had been based. According to the necrotic portion of femoral head, and on the basis of the catterallclassification, LCP was graded 1 to 4, as follows: Grade I=0~ <25%; II=2 5~ <50%; III=50~ <75; IV=75-100%. Using atransparent paper on which 1mm squares had been drawn, the necrotic area of each MR image was measured; thefollowing equation was then used to calculate the volume of the necrotic portion: volume=necrotic area x slicethickness. On the basis of this measurement, each femoral head was graded and the results were compared with thoseobtained using the Catterall classification. RESULTS: In 24 joints(85.7%), grades according to the Catterallclassification and MRI volume measurement were not the same. As compared with the volume measurement method, useof the Catterall classification led to grade overestimation in 18 joints (64.3%) and underestimation in six(21.4%). CONCLUSION: The grade according to the Catterall classification was different from that obtained usingthe volume measurement method. This study thus indicates the need for a new system of classifying LCP diseasebased on the volume measurement method and using MR imaging.