Time to parathyroid function recovery in patients with protracted hypoparathyroidism after total thyroidectomy

Objective: Hypocalcaemia is the most common adverse effect after total thyroidectomy. It recovers in about two-thirds of the patients within the first postoperative month. Little is known, however, about recovery of the parathyroid function (RPF) after this time period. The aim of the present study was to investigate the time to RPF in patients with protracted (>1 month) hypoparathyroidism after total thyroidectomy. Design: Cohort prospective observational study. Methods: Adult patients undergoing total thyroidectomy for goitre or thyroid cancer. Cases with protracted hypoparathyroidism were studied for RPF during the following months. Time to RPF and variables associated with RPF or permanent hypoparathyroidism were recorded. Results: Out of 854 patients undergoing total thyroidectomy, 142 developed protracted hypoparathyroidism. Of these, 36 (4.2% of the entire cohort) developed permanent hypoparathyroidism and 106 recovered: 73 before 6 months, 21 within 6-12 months and 12 after 1 year follow-up. Variables significantly associated with RPF were the number of parathyroid glands remaining in situ (not autografted nor inadvertently resected) and a serum calcium concentration >2.25 mmol/L at one postoperative month. Late RPF (>6 months) was associated with surgery for thyroid cancer. RPF was still possible after one year in patients with four parathyroid glands preserved in situ and serum calcium concentration at one month >2.25 mmol/L. Conclusions: Permanent hypoparathyroidism should not be diagnosed in patients requiring replacement therapy for more than six months, especially if the four parathyroid glands were preserved.