Parathyroid hormone deficiency after total thyroidectomy: incidence and time.

BACKGROUND: Parathyroid hormone (PTH) deficiency or hypoparathyroidism after total thyroidectomy is not an uncommon postoperative complication. Patients who have PTH deficiency will develop profound hypocalcemia if not properly treated with oral calcium supplementation and activated vitamin D (1,25-dihydroxycholecalciferol or calcitriol). However, there is little published on the long-term outcomes of these patients. The aim of this study was to determine the incidence of PTH deficiency and the time course to resolution after total thyroidectomy.
METHODS: We identified 271 consecutive patients who underwent total thyroidectomy from January 2006 to December 2008. All patients had serum PTH levels tested 4 h after surgery and the morning after surgery. Patients were diagnosed with PTH deficiency if their serum PTH was <10 pg/mL. The outcomes of patients with PTH deficiency (group 1) were then compared with patients who did not have PTH deficiency (group 2). Patients in group 1 were evaluated for parathyroid function by measuring serum PTH levels as well as documenting usage of supplemental calcium and 1,25-dihydroxycholecalciferol.
RESULTS: Of the 271 patients, 33 (12%) were found to have PTH deficiency. In comparing PTH deficient patients (group 1) with patients in group 2, there were no differences in age, gender, thyroid pathology, the incidence of thyroiditis, or other factors that would predict hypoparathyroidism. Twenty-four patients (73%) had recovery of their PTH levels to > or =10 pg/mL at their 1 wk follow-up appointment, while 9 (27%) patients still had PTH levels <10 pg/mL. With long term follow-up, 27 (82%) patients had recovered with a PTH level of > or = 10 pg/mL, while 6 (18%) patients had a serum PTH level <10 pg/mL. However, three of the 33 patients in group 1 (9%) required long-term 1,25-dihydroxycholecalciferol, but only two of these patients had undetectable PTH levels. Thus, the overall rate of hypocalemia requiring 1,25-dihydroxycholecalciferol was <1% (two of 271 total patients).
CONCLUSIONS: We concluded that approximately 12% (33 of 271) of patients undergoing total thyroidectomy will develop PTH deficiency. Of the PTH deficient patients, 73% will return to normal parathyroid function within 1 wk of surgery. Furthermore, 82% of these PTH deficient patients will return to normal parathyroid function with long-term follow-up. Less than 1% (two of 271) of patients undergoing total thyroidectomy will require 1,25-dihydroxycholecalciferol for long-term hypocalcemia. Copyright 2010 Elsevier Inc. All rights reserved.