Vertebral Fractures and Bone Mineral Density in Patients With Idiopathic Hypoparathyroidism on Long-Term Follow-Up

Abstract

Context: Bone mineral density (BMD) is increased in idiopathic hypoparathyroidism (IH). Parathyroid hormone (PTH) deficiency, hypocalcemic seizures, and anticonvulsants could compromise skeletal health in IH.

Objective: We assessed vertebral fractures (VFs) and related factors in IH and change in BMD during follow-up.

Design: VFs were assessed by morphometry. BMD was assessed by dual-energy X-ray absorptiometery at the lumbar spine, hip, and forearm. Change in BMD was assessed in a subset after a 10-year follow-up.

Setting: The endocrine clinic of All India Institute of Medical Sciences, New Delhi, India.

Subjects: Included were 104 patients with IH and 64 healthy controls. Hypocalcemia, hyperphosphatemia, normal kidney function, and low serum PTH levels were used to diagnose IH.

Results: VFs were seen in 18.3% of patients with IH and 4.7% of controls (odds ratio, 4.54; 95% confidence interval, 1.28 to 16.04). Use of anticonvulsants and menopause were significantly associated (P < 0.05) with VF. Mean BMD at lumbar spine and hip were higher by 21.4% and 8.6%, respectively, in IH than in controls (P < 0.001), respectively. BMD significantly increased during follow-up at all sites. Change in BMD correlated with maintenance of the serum calcium/phosphorus ratio during follow-up.

Conclusions: Despite increased BMD, prevalence of vertebral-fractures is greater in patients with IH, especially in postmenopausal women and those on anticonvulsant therapy.