How frequently does parathyroidectomy and adjuvant treatment lead to clinically meaningful changes in bone mineral density? A multi-institutional study.

BACKGROUND: The US Food and Drug Administration adopted percentage change in total hip bone mineral density as a validated surrogate end point to support clinical trials for osteoporosis. We evaluated the impact of parathyroidectomy for primary hyperparathyroidism on bone density using this new standard, with or without bisphosphonate therapy. METHODS: We included 490 adults who underwent curative parathyroidectomy at 3 institutions and had bone mineral density testing within 3 years before and after surgery. We calculated the proportion achieving ≥3.18% improvement in total hip bone mineral density, with subgroup analyses by bisphosphonate use before and after surgery. RESULTS: Mean age was 66.9 years, and mean preoperative calcium was 10.7 mg/dL. Overall, 45.2% (95% credible interval, 40.8%-50%) achieved meaningful bone mineral density improvement within 3 years. Among patients not on bisphosphonates preoperatively, rates were similar whether bisphosphonates were never used (43.3%), started within 1 year (53.6%), or beyond 1 year after surgery (48.5%). For patients on bisphosphonates preoperatively, improvement occurred in 37.9% if discontinued postoperatively, 36.1% if restarted within 1 year, and 46.8% if restarted after 1 year. CONCLUSION: Parathyroidectomy alone results in clinically meaningful bone mineral density improvement in 45.2% of patients. The additive benefit and optimal timing of bisphosphonates remain uncertain, underscoring the need for better adjuvant strategies, with respect to bone health, to enhance skeletal recovery after surgery.