Pre-closure parathyroid hormone assay in predicting post-operative hypocalcemia

Background:Transient asymptomatic hypocalcaemia occurs in most patients undergoing thyroidectomy. Symptom occurrence is variable and depends on the rate and decrement of the drop in ionized calcium. The objective was to find the sensitivity and specificity of pre-closure PTH in predicting post-operative hypocalcaemia.  Methods:This is a case control study done in department of surgery medical college Thiruvananthapuram. Study was designed as per the STARD guidelines. 40 patients who have undergone total thyroidectomy, near total thyroidectomy and completion thyroidectomy during one year study period with post-operative hypocalcemia and  pre closure PTH value assayed were selected and compared with  100 patients without post-operative hypocalcemia The data collected were analyzed and sensitivity and specificity of parathyroid hormones in predicting hypocalcaemia was calculated and ROC curve plotted.Results:The sensitivity we found out was that pre-closure PTH assay in predicting hypocalcemia is 100% and specificity 96%. After analyzing the ROC curve we found out that if the lower value of pre-closure PTH is taken as 9.05 pg/ml the test has 100% sensitivity and specificity.Conclusion:Pre closure PTH assay is an excellent investigation to predict post- operative hypocalcaemia in patients undergoing thyroidectomy.