Parathyroid Hormone as a Predictor of Hypocalcemia after Thyroidectomy

OBJECTIVES: The aims of this study are to ascertain whether parathyroid hormone (PTH) assay before total/completion thyroidectomy followed by levels immediately thereafter in the recovery room and the morning after surgery are a reliable predictor of hypocalcemia at our institution. In addition, to determine the feasibility of early discharge home from hospital after total thyroidectomy on the basis of postoperative PTH levels. STUDY DESIGN: Prospective clinical study. METHODS: Two hundred one patients undergoing total thyroidectomy at our institution were enrolled in the study. Preoperative levels of PTH, serum calcium, ionized calcium, and albumin were drawn. In the postoperative phase, the same biochemical markers were taken in the recovery room within 1 hour of the procedure and at a standard time the morning after the procedure. Discharge planning took place as per existing standards. RESULTS: Two hundred and one patients were reviewed. PTH levels below 1.1 pmol/L within 1 hour of completion or total thyroidectomy were predictive of risk for developing hypocalcemia, requiring calcium replacement therapy. PTH levels above 1.6 pmol/L were predictive of patients who would remain normocalcemic. Patients who fell in between these two values require further monitoring with conventional calcium levels. CONCLUSIONS: At our institution, PTH assays drawn postoperatively are predictive of patients who are at risk for developing hypocalcemia. Early identification of at-risk patients will facilitate prompt calcium replacement therapy and potential safe early discharge from hospital.