Comparative Study of Urinary Minerals and Their Effect on Stone Formation in Two Groups of Cystic Fibrosis (CF) and Healthy Children

Abstract

Background: Cystic Fibrosis (CF) is a systemic autosomal disorder and the most important chronic lung disease in children. Oxalate is the end product of vitamin C metabolism, which increases the risk of kidney stones, urinary bladder stones, and calcium deposits in CF patients. Objectives: Considering the increased mineral excretion and the rate of stone formation in the urinary tract, examining the excretion of minerals will greatly help resolve clinical problems. Methods: This descriptive-analytical study was performed on CF and healthy children in Gorgan in 2018 - 19. In this study, 40 CF children and 40 healthy children were randomly selected. After obtaining informed consent from the parents of the children, a random urine sample was collected to evaluate urine minerals. Children with abnormal urinary mineral excretion underwent ultrasonography. The data were analyzed by SPSS 18 using descriptive indices (mean ± SD, frequency, and percentage) and statistical tests (independent t-test, chi-square test, and nonparametric tests). Results: Out of 80 CF and healthy children, 34 were girls, and the rest was boys. The mean age of the patients was 4.34 ± 3.38. The age difference was not significant between the groups (P > 0.05). The mean urinary levels of phosphorus, uric acid, magnesium, and citrate were 0.87 ± 1.01, 1.16 ± 0.68, 0.23 ± 0.18, 2.37 ± 3.13 mg/mg of creatinine. In the pediatric patient group, respectively (P < 0.001). The mean urinary calcium level in CF patients was 0.28 ± 0.39, which was lower than that in the healthy group. The mean urinary oxalate level was 0.13 ± 0.20 in CF patients, which was higher than that in the healthy group (P > 0.05). Hyperoxaluria, hyperuricosuria, hypomagnesiuria, and hypocitraturia occurred in 35, 30, 62, and 7.5% of the CF patients, respectively. Among the urinary minerals studied, hyperoxaluria was found to be a major determinant of stone formation risk in CF. No correlation was observed between the formation of stones and the rate of excretion of minerals (P > 0.05). Conclusions: In summary, CF patients are at an increased risk of developing citrate and calcium stones compared to the healthy group, which is associated with hyperuricosuria, hypocitraturia, and hyperoxaluria.