Factors Associated With the Lower Prevalence of Nephrolithiasis in Children Compared With Adults

Abstract

To determine the reasons behind the lower prevalence of kidney stones in children by assessing urinary lithogenic parameters in healthy children, healthy adults, and 3 groups of stone-former patients. The study subjects included 75 healthy adults, 105 healthy children, 62 patients with previous calcium oxalate monohydrate papillary stones, 120 patients with previous calcium oxalate monohydrate unattached stones, and 248 patients with previous calcium oxalate dihydrate stones. Twenty-four-hour urine samples were collected, and the urinary lithogenic parameters were measured. Calcium, magnesium, and phosphorous concentration differed significantly between healthy children and adults. Except citrate, all solute/creatinine ratios differed between healthy children and adults. However, these differences were much more important in the cases of calcium and magnesium. The calcium/creatinine ratio was 2-fold lower, whereas the magnesium/creatinine ratio was 2-fold higher, in healthy children than that in healthy adults (P <.001 each). The calcium/creatinine ratio was higher and the citrate/creatinine ratio lower in calcium oxalate dihydrate stone formers than that in healthy adults. Ratios of calcium and magnesium to creatinine, as well as morphoanatomic factors and lifestyle habits, may explain the lower prevalence of nephrolithiasis in children than those in adults.