Safety of surgery for managing hyperthyroidism in patients with or without preoperative euthyroidism: A systematic review and meta-analysis

BACKGROUND: Guidelines recommend achieving normal thyroid function (euthyroidism) before thyroid surgery to treat hyperthyroidism due to concerns about uncontrolled thyroid hormone release during surgery. However, achieving euthyroidism before surgery may not always be possible. We aim to evaluate postoperative outcomes of hyperthyroid patients who were euthyroid versus those who were not before thyroid surgery.

METHODS: We searched Medline, Embase, Scopus, and Cochrane from inception to July 2023 to identify comparative studies on hyperthyroid patients who were euthyroid or hyperthyroid (elevated thyroxine levels) before surgery. We evaluated post-surgical complication rates in each group. A random-effects model was used to consolidate dichotomous variables with odds ratios (OR) and continuous variables with mean differences (MD), both with 95% confidence intervals (95% CI). The risk of bias was assessed using the Newcastle-Ottawa Scale.

RESULTS: We included eight retrospective cohort studies involving 1336 patients, of whom 33.6% (n = 449) were biochemically hyperthyroid at the time of thyroidectomy. Most of these patients were female (67.2%, n = 899), with an average age (SD) of 38.73 ± 2.80 years, and had Graves' Disease (96%). The mean (SD) preoperative TSH was 0.28 ± 0.10 mIU/L, FT4 was 3.33 ± 0.64 ng/dL, and FT3 was 67.65 ± 22.41 pg/mL. No significant differences were observed in postoperative complications between preoperatively euthyroid and hyperthyroid patients. This includes temporary hypocalcemia (OR: 0.50, 95% CI: 0.20-1.29, I 2: 42.7%, n = 521), permanent hypocalcemia (OR: 0.46, 95% CI: 0.11-1.96, I 2: 0.0%, n = 727), temporary hoarseness (OR: 1.46, 95% CI: 0.59-3.64, I 2: 0.0%, n = 541), permanent hoarseness (OR: 0.74, 95% CI: 0.13-4.34, I 2: 0.0%, n = 727), bleeding risks (OR: 0.27, 95% CI: 0.06-1.28, I 2: 0.0%, n = 541), length of hospital stay (MD: 0.0, 95% CI: -0.2-0.2, n = 379), and operative time (MD: -5.6, 95% CI: -15.4-4.3, n = 674). There was one case of thyroid storm after surgery in the hyperthyroid group, with no mortalities reported. The risk of bias was moderate in six studies and high in two.

CONCLUSIONS: Low-to-moderate quality evidence suggests preoperatively euthyroid patients undergoing total thyroidectomy have lower risks of hypocalcemia, hoarseness, and hematoma than hyperthyroid patients, though differences are not statistically significant. These findings can guide recommendations for hyperthyroidism management and help clinicians weigh surgical risks and benefits for hyperthyroid patients.