Romosozumab Treatment after Parathyroidectomy for Primary Hyperparathyroidism-complicated Osteoporosis: A Two-Case Report

Background/Objective: Parathyroidectomy increases bone mineral density (BMD) by 3-4% in patients with primary hyperparathyroidism (PHPT); however, limited studies have demonstrated the effect of postoperative medical therapy, particularly with bisphosphonate and denosumab, on BMD.Herein, we report two cases of PHPT in which romosozumab, an anti-sclerostin antibody, increased BMD after parathyroidectomy.Case report: Case 1.A 67-year-old woman was diagnosed with PHPT and advanced osteoporosis, with T-scores of -4.0 and -5.4 in the lumbar spine (LS) and distal radius (DR), respectively.After parathyroidectomy and 5-year treatment with eldecalcitol and raloxifene, T-scores were -3.3 and -5.6 in the LS and DR, respectively.Thereafter, 12-month romosozumab therapy with eldecalcitol increased BMD by 25.2% (0.717 to 0.898 g/cm 2 ) and 4.0% (0.351 to 0.365 g/cm 2 ) in the LS and DR, respectively.Case 2. A 64-year-old woman was diagnosed with PHPT and advanced osteoporosis, with T-scores of -4.1 and -4.9 in the LS and DR, respectively.Four months after parathyroidectomy, 12-month therapy with romosozumab and eldecalcitol increased BMD by 30.1% (0.602 to 0.783 g/cm 2 ) and 4.3% (0.532 to 0.555 g/cm 2 ) in the LS and total hip, respectively.Discussion: We present the first reported cases of PHPT-complicated osteoporosis in which BMD improved after romosozumab treatment markedly in the LS by 25-30%.These cases suggest that postoperative romosozumab therapy may be a potential therapeutic option in patients with PHPT and osteoporosis. Conclusion:Romosozumab may be a promising postoperative therapy for patients with PHPT and osteoporosis.