Outcome of protracted hypoparathyroidism after total thyroidectomy

Background: Although the variables that influence the development of post-thyroidectomy hypocalcaemia are now better understood, the risk factors and long-term outcome of persistent hypoparathyroidism (HPP) are poorly defined. A retrospective review of a prospective protocol for the management of post-thyroidectomy hypocalcaemia was performed. Methods: Patients with a serum calcium level below 8 mg/dl (2 mmol/l) 24 h after total thyroidectomy were prescribed oral calcium with or without calcitriol and followed for at least 1 year. Protracted HPP was defined as an intact parathyroid hormone (iPTH) level below 13 pg/ml and need for calcium medication at 1 month after thyroidectomy. Results: Of 442 patients (343 with goitre, 99 with carcinoma) undergoing total thyroidectomy, 222 (50.2 per cent) developed postoperative hypocalcaemia. Eleven patients were lost to follow-up. Parathyroid function recovered in 131 patients within 1 month and 80 developed protracted HPP, which was associated with lymphadenectomy, fewer than three glands left in situ and incidental parathyroidectomy. Parathyroid function recovered within 1 year in 78 per cent of patients with protracted HPP. Factors associated with late recovery of parathyroid function were higher serum calcium and low but detectable iPTH levels 1 month after surgery. These factors were associated with higher calcitriol and calcium dosages at hospital discharge. Parathyroid autotransplantation did not protect against permanent HPP. Conclusion: Higher serum calcium levels at 1 month after total thyroidectomy are associated with recovery of parathyroid function. It is hypothesized that intensive medical treatment of hypocalcaemia - 'parathyroid splinting' - may improve the outcome of patients with protracted HPP.