Original Research

Calcified Tissue International

, Volume 95, Issue 2, pp 141-152

First online:

Increased Trabecular Volumetric Bone Mass Density in Familial Hypocalciuric Hypercalcemia (FHH) Type 1: A Cross-Sectional Study

  • Niels Frederik Breum JakobsenAffiliated withDepartment of Endocrinology and Internal Medicine, Aarhus University Hospital
  • , Lars RolighedAffiliated withDepartment of Surgery P, Aarhus University Hospital
  • , Emil MoserAffiliated withDepartment of Endocrinology and Internal Medicine, Aarhus University Hospital
  • , Peter H. NissenAffiliated withDepartment of Clinical Biochemistry, Aarhus University Hospital
  • , Leif MosekildeAffiliated withDepartment of Endocrinology and Internal Medicine, Aarhus University Hospital
  • , Lars RejnmarkAffiliated withDepartment of Endocrinology and Internal Medicine, Aarhus University Hospital Email author 

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Abstract

Familial Hypocalciuric Hypercalcaemia (FHH) Type 1 is caused by an inactivating mutation in the calcium-sensing receptor (CASR) gene resulting in elevated plasma calcium levels. We investigated whether FHH is associated with change in bone density and structure. We compared 50 FHH patients with age- and gender-matched population-based controls (mean age 56 years, 69 % females). We assessed areal BMD (aBMD) by DXA-scans and total, cortical, and trabecular volumetric BMD (vBMD) as well as bone geometry by quantitative computed tomography (QCT) and High-Resolution peripheral-QCT (HR-pQCT). Compared with controls, FHH females had a higher total and trabecular hip vBMD and a lower cortical vBMD and hip bone volume. Areal BMD and HRpQCT indices did not differ except an increased trabecular thickness and an increased vBMD at the transition zone between cancellous and cortical bone in of the tibia in FHH. Finite element analyses showed no differences in bone strength. Multiple regression analyses revealed correlations between vBMD and P-Ca2+ levels but not with P-PTH. Overall, bone health does not seem to be impaired in patients with FHH. In FHH females, bone volume is decreased, with a lower trabecular volume but a higher vBMD, whereas cortical vBMD is decreased in the hip. This may be due to either an impaired endosteal resorption or corticalization of trabecular bone. The smaller total bone volume suggests an impaired periosteal accrual, but bone strength is not impaired. The findings of more pronounced changes in females may suggest an interaction between sex hormones and the activity of the CaSR on bone.

Keywords

Hypercalcemia Parathyroid hormone Bone density HRpQCT DXA Familial hypocalciuric hypercalcemia