Parathyroid Hormone Assay in Predicting Post Operative Hypocalcemia After Total Thyroidectomy

Abstract

Objectives: Injury to the parathyroids during thyroidectomy leads to either transient ischemia or even infarction of the glands which results in hypocalcemia. Early identification of post-operative hypocalcemia after thyroidectomy can be achieved by assessing parathormone (PTH) level. The present study correlates post-operative serum PTH at 4 h with serum calcium levels after total thyroidectomy and subsequent development of hypocalcemia. This study thus aims to determine the efficacy of parathyroid hormone assay in predicting post-operative hypocalcemia after total thyroidectomy. Methods: After obtaining approval for the study from the Institutional Review Board, patients admitted in surgery department of Kottayam medical college for total thyroidectomy are evaluated with post-operative PTH levels at 4 h after surgery and serial monitoring of serum calcium levels. Patients are evaluated clinically for signs and symptoms of hypocalcemia and their association is studied. Results: 20% of the study population developed hypocalcemia. Intact PTH was found to be lower in patients who developed symptoms of hypocalcemia. There was a statistically significant correlation between the two groups. A 4-h intact PTH value of 14 pg/mL was found to have high sensitivity (93.8%) and specificity (91.6%). Conclusion: Hypocalcemia is one of the most feared complications after total thyroidectomy. Intact PTH measurement 4 h after total thyroidectomy can be used to predict the incidence of hypocalcemia after total thyroidectomy. Therefore, patients having low 4-h intact PTH value could be started on calcium supplementation and those having high PTH could be safely discharged early.