ESPN 51th Annual Meeting

ESPN 2018


 
Could the association between 25-D levels and urinary calcium/creatinine ratio explain the increased risk of nephro-lithiasis during childhood?
JUSTINE BACCHETTA 1 TIPHANIE GINHOUX 1 LAURENCE DUBOURG 1 CHRISTELLE ROGER 1 MARIE-CHRISTINE CARLIER 1 AURéLIA BERTHOLET-THOMAS 1

1- HOSPICES CIVILS DE LYON ET UNIVERSITé CLAUDE BERNARD LYON 1, LYON, FRANCE
 
Introduction:

The assessment of mineral metabolism and skeletal health is complex in pediatrics. We aimed to provide reference values for the main circulating phosphate/calcium and bone biomarkers (total/bone alkaline phosphatase ALP/BAP, β-crosslaps, osteocalcin, sclerostin, C-terminal and intact FGF23).

Material and methods:

 The single-centre VITADOS study is a cross-sectional evaluation of bone, vessels, nutrition and vitamin D in 100 healthy children and teenagers (50 boys).

Results:

At a median age of 13.9(10.0-17.8) years, in both genders, phosphatemia, tubular phosphate reabsorption, ALP and BAP significantly decreased along puberty. In girls, osteocalcin, β-crosslaps and sclerostin significantly decreased at the end of puberty. In both genders, PTH, 25-D, FGF23, plasma calcium and urinary calcium were not modified by puberty: neither FGF23 nor PTH were associated with age-related changes in phosphate. Notably, 39 and 6 asymptomatic subjects displayed calciuria above the crystallization threshold of 3.8 mmol/L and urinary calcium/creatinine ratio above 0.7 mmol/mmol, respectively. Multivariable analyses performed showed that eGFR, TmP/GFR and PTH were significant predictors for calciuria and urinary calcium/creatinine, whilst 25-D remained a predictor only of urinary calcium/creatinine ratio. Neither bone markers of resorption/formation nor daily calcium intake were able to predict calciuria.

Conclusions:

 This study provides reference data for mineral and bone biomarkers across puberty in healthy teenagers, but also highlights the risk of hyper-calciuria in apparent asymptomatic healthy teenagers, not related to calcium intake but rather to 25-D levels, PTH and TmP/GFR. Future studies are warranted to dissect the underlying mechanisms increasing calciuria in these subjects to promote the prevention of nephrolithiasis.