SAT-389 Clinical and Biochemical Characterization of Risk Factors for Vertebral Fractures in Patients with Hypoparathyroidism

Background: Persistent hypoparathyroidism (PH) is a rare disease due to an impaired secretion of PTH, mostly occurring as a complication of total thyroidectomy. Calcium and calcitriol are currently the most common and inexpensive therapies, although not all the patients easily achieve control of the disease. Recently, our group has reported that BMI at diagnosis can predict calcitriol resistance in PH. Very few studies have been performed with fractures as primary endpoint in hypoparathyroidism, and we still not know if PH could be predisposing to an increased risk of morphometric fractures and possible clinical and biochemical predicting factors. Patients and methods: To that end we retrospectively evaluated the anthropometric, biochemical and fracture characteristics in 71 consecutive patients with PH (F/M= 62/9; median age 58.7 yrs, range: 29-87; 67 with post-surgical PH and 4 with autoimmune PH). All patients were hypoparathyroid from at least one year (median duration of disease: 9 yrs., range: 1-41) and were under standard treatment with calcium and active vitamin D analogs (calcitriol). For each patient anthropometric data (BMI=kg/m2; N= Normal weight patients <25; OO= Obese and overweight patients with BMI > 25) were collected, as well as biochemical parameters, such as calcium (mg/dl) and 25 OH vitamin D (25OHD expressed as ng/ml). We considered well controlled (C) patients with calcium between 8.2 and 9.2 mg/dl and not controlled (NC) under 8.2 or above 9.2 mg/dl. Vertebral fractures (VF) were assessed by a quantitative morphometric approach by using images provided by DXA and classified according to Genant classification. Results: Thirteen out of 71 patients (18%) were fractured. We showed a positive linear correlation in the overall population between BMI and calcitriol intake (p=0.006, CI 95% [1.2-6.9]) while no significant difference in prevalence of VF in OO vs N group (8/40 vs 5/31, p=0.76) was found. However, almost half (6/13, 45%) of patients with VF were OO NC. Moreover, 86% of NC vs only 30% of C fractured patients (6/7 vs 2/6) were OO Discussion: We report a high prevalence of VF in hypoparathyroidism. Moreover, we confirm that increased BMI is associated with higher needs of calcitriol to obtain calcium control. Interestingly, our data suggest for the first time that OO hypoparathyroid patients with NC disease are those at highest risk of fracture. Therefore, in this subset of patients a more intensive and proactive biochemical and bone monitoring should be adviced if these results will be confirmed in larger studies.