Hypocalcaemia following thyroidectomy among patients who have previously undergone bariatric surgery: systematic review and meta-analysis

Abstract Background Hypocalcaemia is a common complication after thyroidectomy. Bariatric surgery is associated with significant changes in calcium metabolism. Some studies have identified bariatric surgery as a risk factor for hypocalcaemia after thyroidectomy. This systematic review and meta-analysis assessed whether a history of bariatric surgery was associated with an increased risk of hypocalcaemia after thyroidectomy. Methods This prospectively registered systematic review (PROSPERO; CRD42021295423) was performed in accordance with PRISMA guidelines. Meta-analysis was undertaken using the Mantel–Haenszel method, with outcomes reported as ORs with 95 per cent confidence intervals. Results Twenty studies were included in the qualitative synthesis. Five studies incorporating 19 547 patients met the inclusion criteria for meta-analysis, of whom 196 (1.0 per cent) had a history of bariatric surgery. Patients with a history of bariatric surgery were more likely to develop hypocalcaemia after thyroidectomy (30.6 versus 13.0 per cent; OR 3.90, 95 per cent c.i. 1.50 to 10.12; P = 0.005). Among those with a history of bariatric surgery, patients who underwent a bypass procedure were more likely to develop hypocalcaemia after thyroidectomy than those who had a restrictive procedure (38 versus 23 per cent; OR 2.12, 1.14 to 3.97; P = 0.020). Conclusion Patients with a history of bariatric surgery have a significantly greater risk of hypocalcaemia after thyroidectomy, with a heightened risk among those who have had a bypass procedure. Surgeons performing thyroid surgery should be aware of the increased risk of hypocalcaemia after thyroidectomy among these patients.