The Utility of Serum PTH Assessment 1 Hour after Total Thyroidectomy

Yang, Yun Su; Lee, Eun Jung; So, Sang Su; Choi, Dong Il; Kong, Il Seung; Hong, Ki Hwan

Abstract

BACKGROUND AND OBJECTIVES: Hypocalcemia is the most frequent complication following total thyroidectomy. This prospective study examines the predictive value of parathyroid hormone (PTH) levels measured 1 hour after surgery. MATERIALS AND METHOD: Twenty-four patients underwent total or near-total thyroidectomy for benign or malignant thyroid tumor in one year. Serum calcium and PTH levels were measured preoperatively and at 1 hour after surgery.
RESULTS
All patients were classified into three groups according to hypocalcemic symptoms and postoperative serum calcium levels. A total of 6 (25%) patients were found with hypocalcemia, as demonstrated by clinical and laboratory findings. PTH levels at 1 hour were below normal level (100%) for 6 of the 6 symptomatic hypocalcemia patients, 5 (45%) of the 11 biochemical hypocalcemia patients, and in 1 (14%) of 7 normocalcemic patients (p=0.002). The sensitivity and specificity of postoperative 1 hour PTH assessment to predict symptomatic hypocalcemia were 100% and 66%. The positive and negative predictive rate of postoperative 1 hour PTH assessment to predict symptomatic hypocalcemia were 50% and 100%.
CONCLUSION
Parathyroid gland insufficiency is the main determinant of transient hypocalcemia after bilateral thyroid surgery. Low PTH level at 1 hour after surgery is therefore a feasible predictor of postoperative symptomatic hypocalcemia and permanent hypoparathyroidism.