Postoperative PTH measurement is not a reliable predictor for hypocalcemia after total thyroidectomy in vitamin D deficiency: prospective study of 203 cases.

Abstract

Several factors have been used to predict post total thyroidectomy (TT) hypocalcemia. Serum intact PTH (PTH) levels <10 pg/mL after TT is considered to be the most accurate predictor. The aim of the present study was to evaluate the accuracy of PTH as a predictor of post-TT hypocalcemia in patients with vitamin D deficiency. The present prospective study was conducted from 2009 to 2011 and included patients undergoing TT for benign goiter. The PTH levels 8 h after TT in patients who were vitamin D sufficient (group A; S Vit D >20 ng/mL) versus those who were vitamin D deficient (group B) were compared. Comparison was also performed between patients belonging to group A and group B who developed hypocalcemia. Appropriate statistical tests were applied. A total of 203 patients (19 males, 184 females) underwent TT; 58.6 % (n = 119) belonged to group A and 41.4 % (n = 84) to group B. Their mean age was 36.81 ± 12.9 years, and the mean duration of goiter was 45.35 ± 54.6 months. Hypocalcemia occurred in 41 patients (20.2 %). Among them 15 belonged to group A and 26 to group B (p = 0.002). The mean PTH in patients who developed hypocalcemia was 12.75 ± 8.91 versus 22.58 ± 15.38 in those who did not develop hypocalcemia (p = 0.00). Furthermore it was seen that the mean PTH in vitamin D sufficient hypocalcemic patients (n = 15) was 7.12 ± 1.79 and that in vitamin D deficient hypocalcemic patients (n = 26) was 16 ± 9.77 (p = 0.001) CONCLUSIONS: Our findings suggest that the fall in PTH after TT in vitamin D deficient patients is unreliable in predicting hypocalcemia and should not be relied on to plan early postoperative discharge.