Quantitative Ultrasound (Qus) of The Calcaneus in Children with Idiopathic Hypercalciuria

Background and Aims: Idiopathic hypercalciuria (IH) is defined as hypercalciuria with no detectable cause. Patients with IH might have low bone mineral density (BMD) with increased fracture risk and tendency to short stature. Our aim was to perform calcaneal quantitative ultrasonometry (QUS) in children with IH and relate to calciuria, body height and number of prevalent fractures (Fx).

Materials and Methods: 11 children (8 girls, 3 boys; mean age 11.3±3.1 y) with IH (calciuria>0.1 mmol/kg/24h) were enrolled. The patients were not receiving any drugs known to influence bone metabolism. Fx was 1.4±1.2 per patient. Body height was recorded and QUS was measured on both heels with Cuba Clinical. The 24-h U-Ca excretion (U-Ca/24 h) was assessed and calculated in mmol/kg/24 h. Results were expressed as Z-scores ± SD and matched to values of healthy European pediatric population.

Results: Body height was normal for chronological age (p=0.96). Broadband ultrasound attenuation (BUA), either age-related of height-adjusted, was normal (p=0.18 and 0.26, respectively). Velocity of sound (VOS), either age-related of height-adjusted, was low (p=0.002 and p=0.003, respectively). We found no correlations between Fx and BUA or Fx and VOS (either age-related or height-adjusted) (r =0.01 and 0.02; r =0.32 and 0.26 ). Neither were there any correlations between U-Ca and Fx (r =0.28), or U-Ca and BUA (r =0.21 and 0.32) or VOS (r =0.40 and 0.42), respectively.

Conclusions: Contrary to previous observations where dual-energy X-ray absorptiometry (DXA) was used for BMD evaluation, we found only mild decrease in one QUS parameter with no relationship to fracture rate or calciuria. Children with IH have normal values of BUA and low VOS, not related to calciuria and Fx. QUS is not a surrogate to DXA and its role needs to be further clarified.