Pre-operative serum alkaline phosphatase as a predictive indicator of post-operative hypocalcaemia in patients undergoing total thyroidectomy

Objective:: This study aimed to evaluate whether a pre-operative elevated serum alkaline phosphatase level is a potential predictor of post-operative hypocalcaemia after total thyroidectomy. 

Methods:: Data was retrospectively collected from the case notes of patients who had undergone total thyroidectomy. Patients were divided into Graves’ disease and non-Graves’ groups. Pre-operative and post-operative biochemical markers, including serum calcium, alkaline phosphatase and parathyroid hormone levels, were reviewed. 

Results:: A total of 225 patients met the inclusion criteria. Graves’ disease was the most common indication (n = 134; 59.5 per cent) for thyroidectomy. Post-operative hypocalcaemia developed in 48 patients (21.3 per cent) and raised pre-operative serum alkaline phosphatase was noted in 94 patients (41.8 per cent). Raised pre-operative serum alkaline phosphatase was significantly associated with post-operative hypocalcaemia, particularly in Graves’ disease patients (p < 0.05).

Conclusion:: Pre-operative serum alkaline phosphatase measurements help to predict post-thyroidectomy hypocalcaemia, especially in patients who do not develop hypoparathyroidism. Ascertaining the pre-operative serum alkaline phosphatase level in patients undergoing total thyroidectomy may help surgeons to identify at-risk patients.