Weight gain after curative parathyroidectomy predicts increase in bone mineral density in patients with symptomatic primary hyperparathyroidism

BACKGROUND Primary hyperparathyroidism (PHPT) results in reduction of bone mineral density (BMD) and an increased risk of pathological fractures. Curative surgery does improve BMD; however, the magnitude of rise and predictive factors are highly variable amongst the hitherto available studies. OBJECTIVES To quantify the magnitude of improvement in BMD after curative surgery in patients with symptomatic PHPT and dissect out the possible clinical and biochemical parameters predicting the BMD rise. METHODS We conducted a retrospective study of symptomatic PHPT patients undergoing surgery between August 2016 and July 2018. Patients achieving biochemical cure with pre- and post-operative (at least 1 year after surgery) dual-energy X-ray absorptiometry scans performed were included in the study. RESULTS After exclusion, 63 patients were included in the study (M:F = 2:5; mean age = 44.8 years). At a median interval of 15 months, the median per cent change in BMD (ΔBMD) at lumbar spine (LS), total hip (TH), femoral neck (FN) and one-third distal radius (forearm) was 6.5%, 7.0%, 8.1% and 6.9%, respectively. Following multiple linear regression analysis, baseline BMD was found to inversely predict ΔBMD at LS, TH and forearm. Pre-operative iPTH positively predicted ΔBMD at LS and FN. Interestingly, 82.5% of the patients had a gain in body weight following curative surgery and change in body weight emerged as a significant positive predictor of ΔBMD at all sites. CONCLUSIONS Curative surgery improves BMD at all sites in patients with symptomatic PHPT. Weight gain following surgery can be used as a positive clinical predictor of BMD rise.