Incidence and risk factors for post-thyroidectomy hypocalcemia

Abstract

Objectives. This study aimed to determine the incidence and risk factors for post-thyroidectomy hypocalcemia. Methodology. This was a retrospective study of 242 patients who underwent total or completion thyroidectomy from 2011-2014 at the St. Luke’s Medical Center, Quezon City, Philippines. The overall and type-specific incidences of hypocalcemia were determined. Patient and surgery-related factors were assessed and hypocalcemic events described. Results. Overall incidence of hypocalcemia is 11.98% distributed into symptomatic (10.74%) and asymptomatic (1.24%). The following patient-related factors were not found to be significantly associated with hypocalcemia: age, gender, thyroid disease and thyroid gland weight. Among surgery-related factors, the presence of concomitant complications of thyroidectomy (hoarseness and/or hematoma) and inadvertent parathyroidectomy were significantly associated with hypocalcemia both in the univariate [p=0.046; OR 2.369 (95%CI: 0.995-5.643) and p=0.027; OR 2.426 (95%CI: 1.084-5.432), respectively] and multivariate analyses [p=0.025; OR 2.842 (95%CI: 1.142-7.069) and p=0.013; OR 2.941 (95%CI: 1.252-6.907), respectively]. Other surgery-related factors were not found to be significantly associated with hypocalcemia: extent of thyroidectomy [total vs completion]; neck dissection; surgery duration (hours); and surgeon [consultant vs. trainee]. Among those with symptomatic hypocalcemia, manifestations occurred 29.85±23.07 hours post-operatively and these were: Chvostek’s (80.8%), acral paresthesia (76.9%), perioral numbness (46.1%), carpopedal spasm (15.3%), Trousseau’s (7.7%) and cramps (3.8%). Those who presented with manifestations of hypocalcemia but with normal serum iCa post-operatively comprised 33.9% of the study population and the majority presented with Chvostek’s sign (52%) and acral paresthesia (50%). Conclusion. In this study, hoarseness and/or hematoma and inadvertent parathyroidectomy are risk factors for postthyroidectomy hypocalcemia. Closer monitoring of these patients for hypocalcemia may be necessary.