Parathyroid hormone as a predictor of post-thyroidectomy hypocalcemia

Introduction and objective: The risk of developing hypocalcemia is the reason for prolonged hospitalisation after total thyroidectomy. The objective of this study was to validate parathyroid hormone measurement for predicting post-thyroidectomy hypocalcemia. Material and methods: Eighty-two patients who underwent total or completion thyroidectomy from February 2009 to March 2010 were enrolled in this prospective study to determine the best timing and cutoff point of parathyroid hormone to predict hypocalcemia. Patients with any condition that could interfere with calcium homeostasis were excluded from the survey. Parathyroid hormone and serum calcium levels were determined preoperatively, immediately after surgery and a number of hours later. Results: Treatment for hypocalcemia was required in 16.7% of patients. A percent of delayed decrease in parathyroid hormone was chosen as the best measurement to predict hypocalcemia. An 80% or higher decrease in delayed parathyroid hormone levels had 100% sensitivity (95% CI: 77.2-100%) and 87% specificity (95% CI: 77-93%) for selecting patients for early discharge. Using this test, 73.2% of the patients could have been discharged 24 hours after surgery. A 98% decrease in delayed parathyroid hormone levels could select candidates for early calcium replacement with 98.6% specificity (95% CI: 92.2-99.7%). Conclusions: The decrease in postoperative delayed parathyroid hormone levels is a good predictor of post-thyroidectomy hypocalcemia. A decrease of 80% or more in delayed parathyroid hormone level is a test with excellent sensibility and specificity for selecting candidates for early discharge. The 98% cutoff point has high specificity for selecting patients for early calcium replacement. (C) 2010 Elsevier Espana, S.L. All rights reserved.