Perioperative Parathyroid Hormone Levels in Thyroid Surgery: Preliminary Report

Objectives/Hypothesis: An immediate method of accurately predicting postoperative hypocalcemia after total thyroidectomy would allow for selective early discharge of patients at low risk. The objective of the study was to determine the utility of perioperative parathyroid hormone measurement in predicting postoperative hypocalcemia after a thyroid surgery that places total parathyroid function at risk. Study Design: Prospective case series. Methods: Twenty-seven patients undergoing total or completion thyroidectomy had three blood samples drawn for parathyroid hormone measurement before dissection, 10 minutes after specimen removal, and in the recovery room. Serial ionized calcium levels were measured in the postoperative period. Preoperative, postresection, and recovery room levels were compared with postoperative ionized calcium levels. Results: The average values before resection, after resection, and in the recovery room were 69.3 (range, 13-163), 42.3 (range, 0-120), and 37.4 (range 7-79) pg/mL, respectively. The incidence of hypocalcemia was 11% (3 of 27 patients). The rate of hypocalcemia was significantly higher (50%) in patients with recovery room parathyroid hormone values of 10 pg/mL or less relative to patients with recovery room parathyroid hormone values greater than 10 pg/mL (4%) in this setting (P = .01). Among patients with a parathyroid hormone value of less than 15 pg/mL in the recovery room, an increasing parathyroid hormone level in the recovery room relative to the level after resection predicted normocalcemia without calcium supplementation on X² analysis (P = .01). Conclusion: The study demonstrated that perioperative parathyroid hormone values can help predict patients who are at highest risk for postoperative hypocalcemia after thyroid surgery.