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.