Does idiopathic hypercalciuria affect bone metabolism during childhood? A prospective case-control study

Background A limited number of studies have evaluated biochemical bone metabolism markers in children with idiopathic hypercalciuria, which in adults has been linked with osteopenia. Our aim was to investigate in children with idiopathic hypercalciuria biochemical markers of bone formation and resorption and the osteoprotegerin (OPG) and soluble receptor activator of nuclear factor kB ligand (sRANKL) system which is involved in the osteoclastogenesis process. Methods A prospective study was conducted on 50 children with idiopathic hypercalciuria and 50 healthy age-, sex-, and Tanner stage-matched control subjects. Following the diagnosis, patients were requested to follow a 3-month dietary recommendation for idiopathic hypercalciuria. In patients, at diagnosis and at 3 months of follow-up, and in controls, bone-related hormones and serum/urine biochemical parameters were studied. The bone formation markers (total ALP and osteocalcin) and the bone resorption markers (β-Crosslaps) and the OPG and sRANKL levels were determined. Results No differences were found in the bone formation markers or OPG and sRANKL between the children with idiopathic hypercalciuria and controls. The β-Crosslaps and the β-Crosslaps/osteocalcin ratio were higher in the patients at diagnosis than in controls ( p = 0.019 and p = 0.029, respectively), with a trend to decrease after the 3-month dietary intervention. The initially increased 24-h urinary Ca in the patients decreased after the 3-month dietary intervention ( p = 0.002). Conclusions Children with idiopathic hypercalciuria had biochemical markers compatible with normal bone formation but increased bone resorption. After a 3-month dietary intervention, the trend observed towards decrease in the serum β-Crosslaps may reflect a beneficial response.