Predicting transient hypocalcemia in patients with unplanned parathyroidectomy after thyroidectomy.

OBJECTIVE: To assess the utility of rapid parathyroid hormone (PTH) values in predicting transient post-operative hypocalcemia in patients with unplanned parathyroidectomy during total or completion thyroidectomy. METHODS: All patients who underwent total or completion thyroidectomy between January 2010 and January 2015 were reviewed. Incidences of post-operative hypocalcemia were compared in patients with and without unplanned parathyroidectomy. Unplanned parathyroidectomy was defined as intra-operative incidental or intentional parathyroidectomy. Logistic regression assessed for predictors of hypocalcemia and optimum amount of calcium supplementation. RESULTS: Thirty-eight (13.6%) patients had evidence of incidental parathyroidectomy and 39/280 (13.9%) patients had parathyroid autotransplantation intra-operatively. Central neck dissection and malignancy were identified as risk factors for unplanned parathyroidectomy (p = 0.001, p = 0.060). Patients with unplanned parathyroidectomy were more likely to have hypocalcemia (p = 0.002) and hypoparathyroidism (p < 0.0005). PTH value was the only significant predictor of hypocalcemia in these patients. In patients with a post-operative PTH of ≤15, initial calcium supplementation ≥ 1000 mg decreased the risk of hypocalcemia (p < 0.05). CONCLUSION: Post-operative PTH value predicts hypocalcemia in patients undergoing total and completion thyroidectomy with unplanned parathyroidectomy. In patients with a post-operative PTH < 15, initial calcium supplementation with ≥1000 mg of elemental calcium is recommended.