Thyroid hormone levels in patients with bipolar disorder: A systematic review and meta- analysis

Abstract

Purpose To investigate the difference of serum thyroid hormone (TH) levels in bipolar disorder (BD) during different mood episodes (depression and mania) compared with healthy control (HC) and among different mood episodes. Methods We systematically searched the electronic databases for studies on the relationship between BD and TH levels. The random effects model and the standardized mean difference were used to combine the effect sizes. Results Serum T3 (standard mean difference [SMD]: -0.52, 95% confidence interval [CI]: -0.86 to -0.18, P = 0.00), FT3 (SMD: -0.55, 95%CI: -1.06 to -0.04, P = 0.04) decreased significantly in BD-depression compared with HC. Serum TSH(SMD: 0.20, 95%CI: 0.04 to 0.36, P = 0.02), FT4 (SMD: 0.42, 95%CI: 0.17 to 0.66, P = 0.00) increased significantly and T3 (SMD: −0.73, 95%CI: −1.37 to -0.08, P = 0.03) decreased significantly in BD-mania compared with HC; FT4 (SMD: 0.85, 95%CI: 0.56 to 1.13, P = 0.00) increased significantly in males; TSH (SMD: 0.49, 95%CI: 0.21 to 0.78, P = 0.00) increased significantly, T3 (SMD: -0.57, 95%CI: -0.86 to -0.29, P = 0.00) and T4 (SMD: -0.68, 95%CI: -1.34 to -0.01, P = 0.05) decreased significantly in females. Serum T3 (SMD: 0.29, 95%CI: 0.12 to 0.46, P = 0.00), FT3(SMD: 0.55, 95%CI: 0.28 to 0.81, P = 0.00) increased significantly in BD-mania than in BD-depression. Conclusion Serum T3 and FT3 levels decreased significantly in BD-depression compared with HC. Serum TSH, FT4 levels increased significantly and T3 level decreased significantly in BD-mania compared with HC. Serum T3, FT3 levels increased significantly in BD-mania than in BD-depression. The fascinating thing was that gender differences may affect the compensatory secretion of BD-mania anterior pituitary hormone. Trial registration number and date of registration for prospectively registered trials No. CRD42022378530 (4 December 2022)