PTH and Hypocalcemia: In a study of 176 patients who underwent total thyroidectomy, the decline in PTH after surgery was a reliable predictor of transient hypocalcemia, and a 71% reduction was proposed as the threshold with the highest sensitivity and specificity.22 Another study from Turkey of 100 patients undergoing total thyroidectomy proposed a drop of intact parathyroid hormone (iPTH) of >85% to be a good predictor of symptoms of hypocalcaemia; however, the postoperative PTH at 1h was equivalent to PTH decline.17