Trabecular bone score and bone mineral density in patients with postsurgical hypoparathyroidism after total thyroidectomy for differentiated thyroid carcinoma.

BACKGROUND: Although bone mineral density is reported to be increased in patients with postsurgical hypoparathyroidism (postsurgical HypoPT), the effect of HypoPT on trabecular bone score remains unknown. This study evaluated the long-term effects of HypoPT secondary to total thyroidectomy for differentiated thyroid cancer on trabecular bone score, bone mineral density, and bone turnover markers with a similar group of patients without HypoPT.

METHODS: Women with resected differentiated thyroid cancer and either postsurgical HypoPT (n = 25; 8 premenopausal and 17 postmenopausal) or euparathyroid function (n = 98; 14 premenopausal and 84 postmenopausal) were matched for age and body mass index. Patients received thyroid-stimulating hormone suppression during follow-up. The bone mineral density and trabecular bone score were analyzed using dual x-ray densitometry and Med-Imaps software at baseline (1-3 months postsurgery) and at the final study visit.

RESULTS: Follow-up duration was similar in studied groups (median 10 years). Baseline bone mineral density and trabecular bone score were similar between HypoPT and non-HypoPT patients, regardless of menopausal status. At study end, postmenopausal HypoPT patients had greater bone mineral density versus the non-HypoPT patients at the lumbar spine, hip, and distal radius (P = .001), and a greater trabecular bone score (1.31 ± 0.09 vs 1.24 ± 0.12, P = .0184). Premenopausal patients with and without HypoPT had similar bone mineral density values at the final evaluation. The bone turnover markers (osteocalcin, bone-specific alkaline phosphatase, and β-crosslaps) were less in postmenopausal HypoPT patients, reflecting decreased bone turnover.

CONCLUSION: Postmenopausal patients who underwent a total thyroidectomy for differentiated thyroid cancer with postsurgical HypoPT have greater trabecular bone score and bone mineral density compared with euparathyroid patients, suggesting that HypoPT protects against the negative effects of long-term thyroid-stimulating hormone suppression treatment on bone.