Kidney volume normative values in Central European children aged 0-19 years: a multicenter study.

BACKGROUND AND OBJECITVES: The currently available kidney volume normative values in children are restricted to small populations from single-centre studies not assessing kidney function and including none or only a small number of adolescents. This study aimed to obtain ultrasound-based kidney volume normative values derived from a large European White/Caucasian paediatric population with normal kidney function. METHODS: After recruitment of 1427 children aged 0-19 years, 1396 individuals with no history of kidney disease and normal estimated glomerular filtration rate were selected for the sonographic evaluation of kidney volume. Kidney volume was correlated with age, height, weight, body surface area and body mass index. Kidney volume curves and tables related to anthropometric parameters were generated using the LMS method. Kidney volume predictors were evaluated using multivariate regression analysis with collinearity checks. RESULTS: No clinically significant differences in kidney volume in relation to height were found between males and females, between supine and prone position and between left and right kidneys. Males had, however, larger age-related kidney volumes than females in most age categories. For the prediction of kidney volume, the highest coefficient correlation was observed for body surface area (r = 0.94), followed by weight (r = 0.92), height (r = 0.91), age (r = 0.91), and body mass index (r = 0.67; p < 0.001 for all). CONCLUSIONS: This study presents LMS-percentile curves and tables for kidney volume which can be used as reference values for children aged 0-19 years.

Effect of Vitamin D Treatment on Dynamics of Stones Formation in the Urinary Tract and Bone Density in Children with Idiopathic Hypercalciuria.

Vitamin D supplementation in patients with urolithiasis and hypercalciuria is considered to be unsafe. We analyzed the impact of vitamin D supplementation on selected health status parameters in children with idiopathic hypercalciuria. The study included 36 children with urolithiasis resulting from excessive calcium excretion. The level of calcium and 25(OH)D (hydroxylated vitamin D - calcidiol) in serum, urinary calcium excretion and the presence of stones in urinary tract were assessed prospectively. Blood and urine samples were collected at the time when the patient was qualified for the study and every three months up to 24 month of vitamin D intake at a dose of 400 or 800 IU/day. At time zero and at 12, and 24 months of vitamin D supplementation, densitometry was performed. Supplementation with vitamin D caused a statistically significant increase in the concentration of 25(OH)D in serum. There were no significant changes in calcium concentration in serum, excretion of calcium in urine but also in bone density. There was no significant increase in the risk of formation or development of stones in the urinary tract. Supplementation with vitamin D (400-800 IU/day) in children with idiopathic hypercalciuria significantly increases 25(OH)D concentration, does not affect calciuria, but also does not improve bone density.

The impact of vitamin D supplementation on vitamin D level, urinary calcium excretion and bone density in patients with hypercalciuria and vitamin D deficiency - preliminary report.

AIM: To study the impact of vitamin D supplementation on vitamin D concentration in plasma, calcium urinary excretion and bone density in patients with urolithiasis in the course of idiopathic hypercalciuria and with a low vitamin D level. MATERIALS AND METHOD: Prospective analysis concerning 28 patients (16 boys, 12 girls) aged 6-14 years (average 10.4) in terms of urinary calcium excretion (mg/kg/day and Ca/Creatinine ratio in morning urine sample), 25OHD blood level after 3, 6, 9 and 12 months of individually recommended doses of vitamin D supplementation (400 IU or 800 IU). The doses were determined on the basis of 25 (OH) D deficiency. The children were on a normocalcemic diet. The bone mineral density of the patients was assessed before and after 12 months of vitamin D use at the aforementioned doses. RESULTS: There was no statistically significant correlation between 25 (OH) D plasma concentration and urinary calcium excretion measured on Ca /Creatinine ratio in daily urine collection and Ca/Creatinine ratio in the morning urine sample. No statistically significant change in calcium excretion was noted (measured by calciuria in daily urine collection and the calcium to creatinine ratio in the morning urine sample). A statistically significant increase in vitamin D plasma concentration was observed. Improvement in bone mineral density was not statistically significant. CONCLUSIONS: Supplementation of vitamin D in the children with idiopathic hypercalciuria and urolithiasis who were examined seems to be safe. The decision to start treatment and the selection of the vitamin D dose should be considered individually. Patients with urolithiasis should be carefully monitored for calcium/phosphate metabolism parameters and the activity of the disease. Supplementation of low doses vitamin D in the children examined did not improve bone mineral density.