Hypocalcaemia following laryngectomy: prevalence and risk factors

Objectives. To establish the prevalence of hypocalcaemia following laryngectomy and demonstrate that total thyroidectomy is a risk factor. Methods. A retrospective cohort study was conducted that included all patients who under- went total laryngectomy from 1st January 2006 to 1st August 2017. Exclusion criteria were: pre-operative calcium derangement, previous thyroid or parathyroid surgery, concurrent glossectomy, pharyngectomy, or oesophagectomy. Results. Ninety patients were included. Sixteen patients had early hypocalcaemia (18 per cent), seven had protracted hypocalcaemia (8 per cent) and six had permanent hypocalcaemia (10 per cent). Exact logistic regression values for hypocalcaemia following total thyroidectomy compared to other patients were: early hypocalcaemia, odds ratio = 15.5 (95 per cent confidence interval = 2.2-181.9; model p = 0.002); protracted hypocalcaemia, odds ratio = 13.3 (95 per cent confidence interval = 1.5-117.1; model p = 0.01); and permanent hypocalcaemia, odds ratio = 22.7 (95 per cent confidence interval = 1.9-376.5; model p = 0.005). Conclusion. This is the largest study to investigate the prevalence of hypocalcaemia following laryngectomy and the first to include follow up of longer than three months. Total thyroidectomy significantly increased the risk of hypocalcaemia at all time frames and independent of other variables.