Incidence and Predictive Factors of Post Thyroidectomy Hypocalcaemia

Abstract

Background: Hypocalcaemia is a frequent complication of thyroidectomy. Although typically transient, it can lead to an increased length of hospitalization, readmission, and in rare cases be permanent with a lifetime supplementation of calcium. Objective: The aim of this study was to determine the incidence of hypocalcaemia in patients undergoing different type of thyroidectomy for different pathologies, in order to determine which are the factors that could be used as predictive factors of post-operative, transient and permanent hypocalcaemia. Materials and Methods: This retrospective study included 461 patients who had undergone thyroidectomy at the surgical department “A” in IbnSina Hospital between January 2007 to December 2018. The clinicopathologic, biological and surgical details of normocalcemic and hypocalcemic patients were compared. Results: Out of the 461 patients 157 patients (34.1%) developed initial post- operative hypocalcaemia, 149 of them (32.3%) were found to have transient hypocalcaemia and 8 of them (1.7%) had permanent hypocalcaemia. Univariate analysis found female gender (p=0.009), preoperative hypocalcaemia (p=0.001), preoperative hyperthyroidism (0.029), bilateral intervention (p<0.01), bilateral central neck dissection (p=0.038) and inadvertent parathyroidectomy (p=0.018) to be significantly associated with transient hypocalcaemia. Multivariate analysis demonstrated that female gender (p=0.047 OR: 2.87 CI 95% [1.01-8.15]), preoperative hypocalcaemia (p=0.001 OR: 22.21 CI 95% [3.58-137.72] ) and bilateral intervention (p=0.002 OR: 15.66 CI 95% [2.81-87.27] ) were independent significant factors.In addition suspected lesion of the RLN during surgery was a significant factor for post-operative dysphonia on univariate analysis. Conclusion: In conclusion female gender, preoperative hypocalcaemia and bilateral intervention increase the risk of developing transient hypocalcaemia. Preoperative evaluation of calcemia should be systematic and preoperative management of hypocalcaemia should be initiated in patients that are at high risk of developing hypocalcaemia after thyroidectomy.