Better consenting for thyroidectomy: who has an increased risk of postoperative hypocalcaemia?

Hypocalcaemia is the most common complication following thyroidectomy. This study aimed to establish the factors associated with increased risk of hypocalcaemia on day 1 following thyroidectomy. All patients who underwent thyroidectomy under a single consultant during a 5-year period were included. A multivariate analysis was undertaken to ascertain which variables had the most effect on the risk of hypocalcaemia. A prognosis table was constructed to allow risk to be predicted for individual patients based on these factors. Included in the analysis were 210 procedures and 194 patients. Eighty-two percent of patients had no calcium derangement postoperatively. Fourteen point nine percent were categorised as early hypocalcaemia, 1 % had protracted hypocalcaemia and 2.1 % had permanent hypocalcaemia. For hemi-thyroidectomies 2.8 % had postoperative hypocalcaemia and 0.9 % had permanent hypocalcaemia. The multivariate analysis revealed total thyroidectomy (risk ratio 26.5, p < 0.0001), diabetes (risk ratio 4.8, p = 0.07) and thyrotoxicosis (risk ratio 3.1, p = 0.04) as statistically significant variables for early postoperative hypocalcaemia. Gender as an isolated factor did not reach significance but was included in the model. The p value for the model was p < 1 × 10-12. Total thyroidectomy increases risk of early hypocalcaemia when compared to hemithyroidectomy. Gender, diabetes and thyrotoxicosis were also been found to influence the risk. All of these factors are available pre-operatively and can therefore be used to predict a more specific risk for individual patients. It is hoped that this can lead to better informed consent, prevention and better resource allocation.

How reliably can computed tomography predict thyroid invasion prior to laryngectomy?

OBJECTIVES/HYPOTHESIS: There is little evidence to support the removal of thyroid tissue during total laryngectomy. Although oncological control of the tumor is the priority, thyroidectomy can lead to hypothyroidism and hypoparathyroidism. This study aimed to test the usefulness of preoperative computed tomography in predicting histological invasion of the thyroid. STUDY DESIGN: Ambispective cohort study. METHODS: All patients undergoing total laryngectomy for squamous cell carcinoma at one center from 2006 to 2016 were included. Data were recorded prospectively as part of the patients' standard care, but were collated retrospectively, giving this study an ambispective design. The histology report for thyroid invasion was taken as the gold standard. The computed tomography report was categorized by invasion of tumor into intralaryngeal, laryngeal cartilage involvement, and extralaryngeal tissues. RESULTS: Seventy-nine patients were included. Nine patients had thyroid involvement on histology, translating to an incidence of 11.29% in this population. The positive predictive value for cartilage involvement on computed tomography for thyroid invasion was 52.9% (95% confidence interval [CI]: 28.5%-76.1%) and the negative predictive value was 100% (95% CI: 92.7%-100%).The positive predictive value for extralaryngeal spread on computed tomography for thyroid involvement was 100% (95% CI: 62.9%-100%), and the negative predictive value was also 100% (95% CI: 93.5%-100%). CONCLUSIONS: This study has shown that preoperative computed tomography is an effective method of ruling out thyroid gland invasion. The absence of extralaryngeal spread on computed tomography has been shown to be the most useful finding, with a high negative predictive value and a narrow 95% CI. LEVEL OF EVIDENCE: 4. Laryngoscope, 128:1099-1102, 2018.