Clinical, demographic, and laboratory characteristics of children with nephrolithiasis

Abstract

While the incidence of pediatric kidney stones appears to be increasing, little is known about the demographic, clinical, laboratory, imaging, and management variables in this patient population. We sought to describe various characteristics of our stone-forming pediatric population. To that end, we retrospectively reviewed the charts of pediatric patients with nephrolithiasis confirmed by imaging. Data were collected on multiple variables from each patient and analyzed for trends. For body mass index (BMI) controls, data from the general pediatrics population similar to our nephrolithiasis population were used. Data on 155 pediatric nephrolithiasis patients were analyzed. Of the 54 calculi available for analysis, 98 % were calcium based. Low urine volume, elevated supersaturation of calcium phosphate, elevated supersaturation of calcium oxalate, and hypercalciuria were the most commonly identified abnormalities on analysis of 24-h urine collections. Our stone-forming population did not have a higher BMI than our general pediatrics population, making it unlikely that obesity is a risk factor for nephrolithiasis in children. More girls presented with their first stone during adolescence, suggesting a role for reproductive hormones contributing to stone risk, while boys tended to present more commonly at a younger age, though this did not reach statistical significance. These intriguing findings warrant further investigation.

Keywords: Adolescents; Kidney stones; Nephrolithiasis; Obesity; Pediatrics; Urolithiasis.

Fig. 1

Age of initial presentation by age range. Boys most commonly present with their first kidney stone during 6–11 years of age while girls most commonly present during adolescence.

Fig. 2

Percent of stone formers and controls who are overweight or obese by age group. A smaller percentage of stone formers are overweight or obese compared with controls in all age ranges.

Fig. 3

Percent of girl and boy stone formers and controls who are underweight (<5^th percentile BMI), normal (5–84^th percentile BMI) and overweight or obese (≥85^th percentile BMI). Girl stone formers are less likely to be overweight or obese than boy stone formers.

Fig. 4

Percentage of specific abnormalities in 24-hour urine chemistry. SS=supersaturation, Ca=calcium, Ox = oxalate, P=phosphate, Citr=hypocitraturia, UA=uric acid.