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Children with idiopathic hypercalciuria (IH) may have a reduced bone mineral density (BMD), which could impact on bone health in adulthood. There is currently no strong evidence for a preferred treatment of such children. The aim of our study was to evaluate the BMD z-score before and after treating children and adolescents with IH with potassium citrate and thiazides. The study consisted of a historical cohort of 80 pediatric patients who were evaluated between October 1989 and November 2010. Bone scanning and densitometry measurements were made with dual-emission X-ray absorptiometry. Lumbar-spine BMD (g/cm(2)) and BMD z-score were evaluated before and after treatment. The t test and Mann-Whitney U test were used for statistical analysis. Forty-three boys and 37 girls were followed for a median time of 6.0 years. Median calcium excretion before and after treatment was 5.0 and 2.6 mg/kg/24 h, respectively. The BMD z-score changed significantly from -0.763 ± 0.954 (mean ± SD) to -0.537 ± 0.898 (p < 0.0001) before and after treatment, respectively. The BMD z-score of the patients improved with treatment, suggesting a beneficial effect and potential need for treatment. However, the lack of a control group points to the need for future studies to corroborate this outcome.

Unlabelled: The association between idiopathic hypercalciuria (IH) and reduced bone mineral density (BMD) has been described in adults and children. Frequently, hypocitraturia (HC) is an associated condition. To determine the effect that HC may have on bone metabolism of these patients, we studied 88 children with IH at diagnosis, divided into the following groups: group 1-44 (50%) patients with associated HC; group 2-44 (50%) patients without HC; group 3 (29 subjects), a healthy control group. Urinary and blood electrolytes, as long as urinary N-telopeptide, were measured. Lumbar spine (L2-L4) and femoral neck bone mineral density (BMD) and bone mineral content (BMC) were measured by dual energy X-ray absorptiometry. There was no difference in age between the three groups (P=0.80), but weight, height, body mass index, and bone age were lower (P<0.01) and serum intact parathyroid hormone (iPTH) was higher (P<0.05) in group 1 than in groups 2 and 3. N-telopeptide, measured in urine, did not differ between groups. The following bone densitometry parameters: lumbar spine BMC, BMC adjusted for height (BMCh), BMC adjusted for width of vertebrae (BMCw) and BMD, as well as femoral neck BMD, were significantly lower in group 1 than in groups 2 and 3 (P<0.01). When we corrected densitometry parameters for height, BMC was lower in group 1 and not in group 2 when compared with controls., Conclusions: Children with IH and associated HC may have a higher risk of bone mass loss and consequent osteopenia. Further studies are needed to assess the role that hypocitraturia may have in this form of bone disease.

Some children with idiopathic hypercalciuria (IH) develop bone alterations at some stage of the disease. The aims of this study were to evaluate bone mass in 88 children with IH (G1) at the time of diagnosis and to compare the findings with data for a control group of 29 normal children (G2). Kidney and bone metabolism markers were measured in both groups, and bone densitometry was performed. Serum alkaline phosphatase, intact parathyroid hormone, urinary calcium and uric acid were significantly higher in G1, whereas urinary volume and urinary citrate excretion were lower. The following densitometric parameters were significantly lower in G1: (1) lumbar spine (L(2)-L(4)) bone mineral density (BMD), bone mineral content (BMC), BMC corrected for height and for width of the vertebra, volumetric BMD (BMDvol), and Z score; (2) whole-body BMD; (3) femoral neck BMD. Lumbar spine BMDvol was reduced (osteopenia) in 35% of the patients compared with G2. N telopeptide, a urinary marker of bone resorption, was significantly higher in G1 than in G2, and was negatively correlated with lumbar spine BMD and BMDvol. Children with urinary lithiasis or idiopathic hyperuricosuria associated with IH showed no significant differences in bone metabolism compared with children without these associations. We conclude that (1) there is an altered bone metabolism in IH, with osteopenia already present at diagnosis in 35% of the patients; (2) N telopeptide is one of the most useful markers of bone alterations in IH, especially at an early stage of the disease; (3) investigation of bone metabolism is necessary in IH to prevent future serious consequences such as osteoporosis and bone fractures.