BACKGROUND
Hyperthyroidism is a condition where the thyroid gland is overactive and produces too much thyroid hormone. The body’s metabolism is speeded up and many organ symptoms are affected, including the heart, muscles, liver and brain. The most extreme and severe result of hyperthyroidism is known as thyroid storm. It is rare and usually associated with some other medical problem. Thyroid storm can result in heart failure and liver failure and can cause death in 25% of patients. Hyperthyroidism can be effectively treated with antithyroid drugs, thyroid surgery or radioactive iodine.

Patients with hyperthyroidism may need to have surgery for non-thyroid reasons. If surgery is needed, it usually is recommended that the hyperthyroidism be treated until thyroid hormone levels are normal (euthyroidism) first. However, the data to support this recommendation is not strong and occasionally urgent surgery is needed in a hyperthyroid patient while their hyperthyroidism is not yet controlled. There have been case reports of thyroid storm occurring in hyperthyroid patients after non-thyroid surgery. This study was done to review the literature regarding adult patients with hyperthyroidism who have surgery and determine whether there is evidence for any treatment prior to surgery to decrease the risk of thyroid storm.

THE FULL ARTICLE TITLE
de Mul N et al 2021 Risk of perioperative thyroid storm in hyperthyroid patients: A systematic review. Br J Anaesth 127:879–889. PMID: 34389171.

SUMMARY OF THE STUDY
This study was a review of the medical literature. A total of 7692 studies were reviewed, but only 57 studies were felt adequate to include in analysis. Most of the studies were of patients undergoing thyroid surgery. The analysis was separated into 5 groups:

Group 1 included untreated hyperthyroid patients, all were single case reports and 5 of 8 patients described developed thyroid storm.

Group 2 included patients treated with antithyroid medications, included 1 series of 272 patients, 1 of whom was switched to iodine and developed thyroid storm.

Group 3 included a total of 290 patients treated only with beta-blockers, none of whom developed thyroid storm.

Group 4 included 25 studies of patients treated with a combination of medications, overall, with 3 patients developing thyroid storm

Group 5 consisted of multiple studies that compared different treatments, none of the patients developed thyroid storm.

They also remarked on two studies of 288 and 266 patients, respectively, who were treated in variable ways, and found no difference in outcome whether patients achieved normal thyroid levels or not prior to surgery.

WHAT ARE THE IMPLICATIONS OF THIS STUDY?
Overall, this study does not identify a specific treatment to recommend before surgery to avoid the complication of thyroid storm. Even when normal thyroid hormone levels are not attained before surgery, the risk of thyroid storm is low. However, it is still recommended that patients be treated and their hyperthyroidism controlled before considering elective surgery, particularly in patients in whom the complications of hyperthyroidism are severe. Patients need to be evaluated individually and discuss with their care team the risks and benefits of surgery when they are hyperthyroid.

— Marjorie Safran, MD

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