Australian Endocrine Surgeons Guidelines AES06/01. Postoperative parathyroid hormone measurement and early discharge after total thyroidectomy: analysis of Australian data and management recommendations

Abstract

Background: The risk of hypocalcaemia after thyroidectomy has traditionally mandated inpatient monitoring for signs and symptoms as well as frequent measurement of serum calcium levels. In recent years there has been much interest in the published work about the use of intact parathyroid hormone (PTH) to better predict hypocalcaemia after thyroidectomy. Although generally accurate, the use of intact parathyroid hormone in Australia has not become widespread. On behalf of the Australian Endocrine Surgeons an analysis of Australian data on the use of PTH levels to predict hypocalcaemia after thyroidectomy was carried out. The data were analysed with a view to making recommendations about the use of this test in clinical practice and the feasibility of achieving safe early discharge for patients.

Methods: Four recently published or presented Australian studies on the use of early postoperative PTH levels after total or completion thyroidectomy to predict post-thyroidectomy hypocalcaemia were analysed. Patients were stratified into either normal or low PTH groups as defined by the normal ranges set by each laboratory and rates of hypocalcaemia were analysed.

Results: A total of 458 patients were examined. Seventy-six per cent of the patients had PTH in the normal range and hypocalcaemia (serum-corrected calcium cCa(2+) < 2.00 mmol/L) occurred in 17.9% of patients. Sensitivity, specificity and positive predictive values of a normal postoperative PTH level as a predictor of normocalcaemia are 92.6, 70.7 and 92.3%, respectively. Low PTH as a predictor of hypocalcaemia is poor. The overall sensitivity, specificity and positive predictive values are 70.7, 92.6 and 71.6%, respectively.

Conclusion: Normal postoperative PTH levels accurately predict normocalcaemia after total or completion thyroidectomy. PTH levels should ideally be drawn 4 h postoperatively and patients with PTH in the normal range can be safely discharged on the first postoperative day. Use of oral calcium supplements, either as needed or routinely, will avoid mild symptoms that may develop in 7% without treatment.