Preoperative parathyroid hormone level as a predictive factor for post-thyroidectomy hypoparathyroidism

Abstract

Purpose: Whether the level of the preoperative parathyroid hormone (PTH) is a risk factor of postoperative hypoparathyroidism remains unclear. The aim of this study was to evaluate the predictive value of preoperative PTH for the hypoparathyroidism following total thyroidectomy. Methods: Five hundred two patients performed total thyroidectomy from January 2009 to July 2010 in Seoul National University Hospital were enrolled. Demographics, operative variables, and the development of hypoparathyroidism were collected and evaluated. Results: A total of 502 patients were enrolled during the study period. Patients had a mean age of 48.1±12.1 years (range, 16 to 95 years) and showed a female predominance (n=420, 83.7%). Preoperative PTH of 44.5 pg/㎖ was recommended as cut-off value. Transient hypoparathyroidism developed 2.4 times (95% confidence interval [CI], 1.1 to 5.1) more frequently in low PTH group (P=0.021). Percentage decline of the preoperative PTH also showed significant association with transient hypoparathyroidism. When the value of 73.9% decline was used, the chance of transient hypoparathyroidism was 3.3 times (95% CI, 2.0 to 5.5) higher in high percentage decline group (P<0.001). Correlation between postoperative PTH level and development of transient hypoparathyroidism was not found (P=0.171). In regard to the permanent hypoparathyroidism, there were no significant differences in all factors. Conclusion: Preoperative PTH level and percentage decline can be used as a predictive factor for postoperative hypoparathyroidism. In patients with low PTH level (<44.5 pg/㎖), caution should be given to prevent injury of the parathyroid glands.

Keywords

• hypoparathyroidism
• predictive value of tests
• complication
• total thyroidectomy
• parathyroid hormone