Evaluation of Perioperative Serum Parathyroid Hormone Levels in Predicting Post-thyroidectomy Hypocalcemia

ABSTRACT

PURPOSE: Postoperative hypocalcemia is one of the most common complications in patients who undergo a bilateral thyroid resection and can prolong hospital stay. However, there is no reliable predictor of clinical hypocalcemia after a thyroidectomy. The aim of this study was to identify the clinical predictors of hypocalcemia after a thyroidectomy and to determine if the perioperative measurements of iPTH would be helpful in identifying patients at risk of post-thyroidectomy hypocalcemia. METHODS: 213 consecutive patients undergoing thyroidectomy between Nov 2004 and Feb 2005 were examined. The iPTH, serum calcium and ionized calcium levels were measured at 6 hours, 1 day and 2 weeks after surgery, respectively. All the patients were divided into the lower PTH group (<10 pg/ml) and normal PTH group according to the level of iPTH measured at 6 hours after surgery. RESULTS: The lower PTH group comprised 33% of all patients 39% after the total thyroidectomy and 11% after a less than total thyroidectomy. The incidence of IV calcium replacement was 36% in the lower PTH group compared with 13% in the normal PTH group. Hypocalcemia and a lowered PTH level occurred more frequently in patients who underwent surgery for a malignant tumor than for a benign tumor. CONCLUSION: There was a correlation between the level of ionized calcium and the incidence of calcium replacement and with the 6 hr-later iPTH level. Therefore, a iPTH levethyroidectomy might predict the development of clinically significant hypocalcemia.