Intact Parathyroid Hormone Levels in Predicting Postoperative Hypocalcaemia After Total Thyroidectomy in South Indian Population: Cross Sectional Study

Hypocalcaemia being one of the most common complications after total thyroidectomy may not be avoidable in all cases. This study evaluated the effectiveness of intact Parathyroid hormone (iPTH) measured at 1-h after total thyroidectomy in predicting postoperative hypocalcaemia in early postoperative period in South Indian population. Patients who underwent total thyroidectomy in our institute from 2016 to 2018 were included. Preoperative calcium and iPTH levels were measured. Patients’ iPTH level was measured 1 h after surgery and serum calcium level was measured at 24 h after surgery. Patients were also monitored clinically for any symptoms and signs of hypocalcaemia. A total of 57 patients were studied. The malignant causes accounted for 75.4% with papillary carcinoma thyroid being the most common cause. 65.7% of patients who underwent total thyroidectomy and 100% of patients who underwent total thyroidectomy with neck dissection developed hypocalcaemia. 70% of patients with low iPTH developed hypocalcaemia and none of the patients who had normal iPTH developed hypocalcaemia. This relation was statistically significant with p value of 0.018 (< 0.05). The positive predictive value is 70% and negative predictive value is 100%. Though our study supports the hypothesis that iPTH is effective in predicting hypocalcaemia after total thyroidectomy in the early postoperative period, a larger sample study is needed to further support this. It can be used to consider patients for early discharge or to prophylactically start oral calcium and Vitamin D supplementation based on iPTH levels at 1 h after surgery.