Hypocalcemia after parathyroidectomy in patients with a history of bariatric surgery

Purpose: A growing body of literature has suggested that a history of bariatric surgery increases the risk of hypocalcemia after subsequent thyroidectomy, however little is known about the risk after parathyroidectomy. The purpose of this study was to determine the incidence of hypocalcemia after parathyroidectomy in patients with prior bariatric surgery. Methods: The TriNetX Research Network was queried using diagnosis and procedure codes to identify patients with a history of bariatric surgery who were subsequently diagnosed with primary hyperparathyroidism (PHP) and underwent parathyroidectomy between 2012 and 2022. The rate of hypocalcemia after parathyroidectomy was compared between those with a history of bariatric surgery and controls who underwent parathyroidectomy alone, matched for demographics, body mass index (BMI) ≥ 30 kg/m², and history of calcium or vitamin D supplementation. Results: There were 34,483 included patients diagnosed with PHP who underwent parathyroidectomy. Of this cohort, 1.4% (n = 472) had prior bariatric surgery. There were 90% females and 10% males in this subset of patients, and the average age was 58 years. Compared to matched controls who underwent parathyroidectomy alone, these patients had a significantly increased risk of hypocalcemia within 0–1 month (RR, 95% CI, P) (17.2% vs. 9.3%; 1.8, 1.3–2.6, P < 0.001), 1–6 months (8.5% vs. 2.5%; 3.3, 1.8–6.3, P < 0.001) and 6–12 months (6.8% vs. 2.3%; 2.9, 1.5–5.7, P < 0.001) following surgery. Conclusion: The current study is the first to indicate that patients with a history of bariatric surgery are at increased risk for short-term and permanent hypocalcemia after parathyroidectomy. Further research is required to determine optimal prevention and treatment strategies to decrease associated morbidity in this subset of patients.