The Safety of Anaesthetising Biochemically Hyperthyroid Patients Undergoing Thyroidectomy—A Retrospective Cohort Study

Traditionally it is recommended that hyperthyroid patients should be made euthyroid prior to thyroidectomy. However, several small observational studies have reported no increase in adverse events when hyperthyroid patients undergo thyroidectomy. The aim of this study was to assess outcomes following total thyroidectomy in patients who were biochemically hyperthyroid at the time of surgery compared to those who were euthyroid. One hundred and fifty-one eligible patients undergoing thyroidectomy for hyperthyroidism between January 2012 and February 2016 were identified, of whom 57 were hyperthyroid on perioperative blood tests and 94 were euthyroid (comparison group). Primary outcomes were 30-day mortality, increased length of postoperative hospital stay and intraoperative signs consistent with thyrotoxicosis (e.g. heart rate >100 per minute, systolic blood pressure >180 or <60 mmHg, or temperature >38°C). Secondary outcomes were intraoperative beta-blocker use and level of care required postoperatively. Thirty-day mortality was zero. The only significant difference between the two groups was a higher use of intraoperative beta-blockers amongst hyperthyroid patients (28.1% versus 8.5%, P=0.002). Our findings suggest that thyroidectomy for mild to moderate biochemical hyperthyroidism performed by an experienced thyroid surgeon and anaesthetist, is associated with increased intraoperative beta-blocker use but no statistical difference in mortality, length of postoperative stay or intraoperative signs consistent with thyrotoxicosis. While we still recommend attempting to achieve a euthyroid state whenever possible prior to thyroid surgery, mild to moderate degrees of residual biochemical hyperthyroidism when appropriately managed may not be associated with an increase in adverse outcomes.

Anaemia and thyrotoxicosis: The need to look for an alternative cause

OBJECTIVES

Anaemia and thyrotoxicosis are both relatively common. It is unclear whether thyrotoxicosis results in anaemia in the absence of other causes. The aim of this study was to determine the prevalence and characteristics of anaemia in patients with thyrotoxicosis.

DESIGN

A prospective cohort study of patients with thyrotoxicosis.

PATIENTS

353 patients referred to a regional endocrinology centre in New Zealand from March 2013 to November 2014 for new-onset thyrotoxicosis.

MEASUREMENTS

Detailed assessment including thyroid function tests, full blood count, inflammatory markers, haematological parameters and coeliac serology. Anaemia was defined as a haemoglobin value <115 g/L (woman) or <130 g/L (men).

RESULTS

Anaemia was present in 31 (8.7%) patients at diagnosis. Of these, pre-existing anaemia was present in 10, and a further 11 had one or more identifiable underlying cause(s) for the anaemia. Only 10 patients (2.8% of the entire cohort) had anaemia not clearly attributable to another cause. Median free thyroid hormone levels were higher in those with anaemia of unknown cause compared to patients with thyrotoxicosis alone. The median duration of anaemia was shorter in patients with thyrotoxicosis-associated anaemia compared to those with anaemia due to an underlying cause (1 vs 6 months, P = .001). In all patients with thyrotoxicosis-associated anaemia, the anaemia resolved, either prior to, or on becoming euthyroid.

CONCLUSION

Anaemia coexisting with thyrotoxicosis is less common than previously reported and is mild and transient. Patients with thyrotoxicosis and significant anaemia should be investigated for other potential causes, particularly when anaemia persists.