Chronic hypoparathyroidism is associated with increased cortical bone density evaluated by high-resolution peripheral quantitative computed tomography

Abstract

Purpose This cross-sectional study aimed to evaluate BMD, bone microarchitecture and prevalent fractures in women with chronic hypoparathyroidism (HypoPT). Methods Twenty-seven women with HypoPT and 44 age-matched healthy women were included. Dual-energy x-rays absorptiometry (DXA) was used to evaluate areal BMD (aBMD) at the spine and hip as well as morphometric vertebral fractures (VFA). Microarchitecture and volumetric BMD (vBMD) were evaluated at distal radius and tibia using high resolution peripheral quantitative computed tomography (HR-pQCT). Biochemical parameters, including FGF23 (fibroblast growth factor 23), CTX (C- terminal telopeptide of type I collagen) and P1NP (procollagen type I N-terminal propeptide), were measured. Previous low-impact fractures were also assessed, and the 10-year fracture risk was estimated using the FRAX tool for Brazilian population. Results There was a low risk of fractures on FRAX tool in all patients, and only two had morphometric vertebral fractures: one patient presented severe VF (T5) and moderate VF (T6); another patient had moderate spinal deformity at T8. No patient had a history of previous clinical fractures. Compared to controls, HypoPT women had higher aBMD in the lumbar spine (p = 0.030), femoral neck and total hip (p < 0.001) and higher cortical vBMD (p = 0.020 in the radius and p < 0.001 in the tibia). Trabecular bone was not affected. Both bone turnover markers P1NP and CTX were compatible with low turnover in the HypoPT patients. However, we found no statistically significant correlations between BMD and any biochemical data, including serum phosphate, CTX and P1NP. Conclusions There was a low prevalence of fragility fractures, compatible with the low fracture risk estimated by FRAX, in the twenty-seven HypoPT women studied. These patients had higher areal BMD and cortical vBMD as compared to controls, but the association with decreased bone turnover was not clear. Future longitudinal studies are needed to clarify the mechanisms involved in the bone fragility described in HypoPT patients.

Incident comorbidities in patients with chronic hypoparathyroidism after thyroidectomy: a multicenter nationwide study

“…Although our data did not show statistically different changes in BMD between both groups, a lower risk of incident fracture in patients with hypoparathyroidism compared to subjects with normal calcium metabolism was found. This finding is in line with a recent study that have shown that prevalence of fragility fractures was low in women with hypoparathyroidism and compatible with low fracture risk estimated by the FRAX tool (39). Taken together, these data suggest, although they do not demonstrate, that hypoparathyroidism protects against fracture risk (32).…”

“…The group NH consisted of 669 patients (568 women, 84.9%) aged between 18 and 79 years (median 47 [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55] years). Demographic and clinical characteristics are shown in Table 1.…”

Hypoparathyroidism update

“…HypoPTH subjects compared with age-matched healthy controls are known to have lower bone turnover [C-terminal telopeptide of type I collagen (CTX), bone-specific alkaline phosphatase, osteocalcin, N-terminal propeptide of type I procollagen (P1NP)], higher areal bone mineral density (aBMD) measured via Dual-energy X-ray absorptiometry at all sites [3], with increasing aBMD with longitudinal follow-up compared with expected age-related bone loss in controls. Volumetric BMD measured via high-resolution peripheral quantitative computed tomography (hrpQCT) at the distal radius and tibia in 27 hypoPTH women and 44 age-matched healthy women noted higher cortical volumetric BMD in both radius (913 vs. 872 mg HA/cm 3 , P ¼ 0.02) and tibia (922 vs. 868 mg HA/cm 3 , P ¼ 0.001) [25]. Trabecular volumetric BMD, trabecular number, trabecular thickness and trabecular bone score were not different, suggestive that PTH has a more potent effect or cortical bone compared with trabecular bone.…”