Percentage Decline of Parathyroid Hormone Level is a Predictor for Post-thyroidectomy Symptomatic Hypocalcemia

Jung, Dami; Kim, Jong kyu; Kwon, Hyungju; Lim, Woosung; Moon, Byung In

Abstract

PURPOSE
Postoperative hypocalcemia is one of the most common complications after thyroid surgery. However, the predictive efficacy of parathyroid hormone (PTH) level was still controversial. We investigated the cut-off value of perioperative PTH level for postoperative hypocalcemia after total thyroidectomy.
METHODS
Four hundred eighty-two patients performed total thyroidectomy from January 2015 to December 2016 were enrolled. Demographics, operative variables and the development of symptomatic hypocalcemia were collected and evaluated.
RESULTS
Transient symptomatic hypocalcemia occurred in 83 (17.2%) patients and 5 (1.0%) patients have progressed to the permanent hypocalcemia. Patients with transient symptomatic hypocalcemia showed significantly lower postoperative day 1 PTH level than those without hypocalcemia (7.7±6.5 vs. 13.1±10.4 pg/mL; P<0.001), while correlation between postoperative PTH level and development of symptomatic hypocalcemia was not found in a multivariate analysis (P=0.122). Percentage decline of the preoperative PTH only showed significant association with transient hypocalcemia and the recommended cut-off value was 75.0%. When percentage decline of 75.0% was used, the incidence of transient hypoparathyroidism was 3.4 times (95% confidence interval, 2.1-5.6) higher in high percentage decline group (P<0.001). In regard to the permanent hypoparathyroidism, there were no significant differences in all factors.
CONCLUSION
Percentage decline of PTH can be used as a predictive factor for postoperative hypocalcemia. Cautions against preventing injury of the parathyroid glands with careful surgical technique should be recommended.