Purpose: Leptin is an important regulator of energy homeostasis, analogous to thyroid hormone (TH). The purpose of this study was to investigate circulating leptin levels in thyroid dysfunction (TD) patients and the role of TH levels.

Methods: The electronic databases PubMed, Embase, Cochrane Library, and Web of Science were independently searched by two researchers, from inception until February 3, 2024, and updated on February 15, 2025. Pooled standardized mean difference (SMD) with a 95% confidence interval (CI) was calculated by the random effects model.

Results: Thirty-eight studies reported circulating leptin levels in TD and control with euthyroidism, 4295 subjects were included in total, of which 1277 were hypothyroidism, 540 were hyperthyroidism, and 2478 were control. Compared to euthyroidism, leptin levels were significantly higher in hypothyroidism, and not significantly altered in hyperthyroidism (SMD [95%CI] = 0.71 [0.38, 1.04] and -0.03 [-0.57, 0.51], respectively). The subgroup analysis indicated that, compared to euthyroidism, leptin levels were significantly higher in subjects regardless of overt and subclinical hypothyroidism (SMD [95%CI] = 0.76 [0.25, 1.26] and 0.41 [0.11, 0.70], respectively), and not significantly different in overt hyperthyroidism (SMD [95%CI] = -0.14 [-0.74, 0.45]). Furthermore, when compared to age-, gender-, and body mass index (BMI)-matched euthyroidism, leptin levels were significantly higher in hypothyroidism and had no significant difference in hyperthyroidism (SMD [95%CI] = 0.66 [0.24, 1.07] and -0.43 [-1.13, 0.27], respectively). A total of 16 studies analyzed the correlations between leptin levels and TH levels in TD, 488 were hypothyroidism and 206 were hyperthyroidism. Following correlation analysis, leptin levels displayed a positive correlation with thyroid-stimulating hormone (TSH) levels (r = 0.19) and a negative correlation with triiodothyronine (T3) levels (r = -0.40) in TD.

Conclusion: Compared to euthyroidism, circulating leptin levels were significantly higher in hypothyroidism, and not significantly altered in hyperthyroidism. Besides, leptin levels in TD may be directly regulated by TSH and T3 levels, independent of BMI.

Trial registration: CRD42024561055.

Keywords: Leptin; Meta-analysis; Thyroid dysfunction; Thyroid hormone.

© 2025. The Author(s).

目的： 腿肽是能量稳态的重要调节因子，类似于甲状腺激素（TH）。本研究旨在调查甲状腺功能障碍（TD）患者循环中的腿肽水平以及甲状腺激素水平的作用。

方法： 两位研究人员独立搜索了PubMed、Embase、Cochrane Library 和 Web of Science 数据库，时间范围从建库开始至2024年2月3日，并于2025年2月15日进行了更新。采用随机效应模型计算汇总标准化平均差（SMD）和95% 置信区间（CI）。

结果： 本研究共纳入了38项关于TD及对照组中甲状腺功能正常情况下循环腿肽水平的研究，共有4295名受试者，其中1277名为甲减患者，540名为甲亢患者，其余为对照组。与甲状腺功能正常相比，甲减患者的腿肽水平显著升高，而甲亢患者的腿肽水平没有显著改变（SMD [95%CI] = 0.71 [0.38, 1.04] 和 -0.03 [-0.57, 0.51]）。亚组分析表明，在与甲状腺功能正常相比，无论是显性甲减还是亚临床甲减患者的腿肽水平均显著升高（SMD [95%CI] = 0.76 [0.25, 1.26] 和 0.41 [0.11, 0.70]），而显性甲亢患者则没有显著差异（SMD [95%CI] = -0.14 [-0.74, 0.45]）。此外，与年龄、性别和体质指数（BMI）匹配的甲状腺功能正常组相比，甲减患者的腿肽水平显著升高，而甲亢患者则没有显著差异（SMD [95%CI] = 0.66 [0.24, 1.07] 和 -0.43 [-1.13, 0.27]）。共有16项研究分析了TD患者的腿肽水平与甲状腺激素水平之间的相关性，其中包括488名甲减患者和206名甲亢患者。经过相关性分析，在TD中，腿肽水平与促甲状腺激素（TSH）水平呈正相关（r = 0.19），与三碘甲状腺原氨酸（T3）水平呈负相关（r = -0.40）。

结论： 与甲状腺功能正常相比，甲减患者的循环腿肽水平显著升高，而甲亢患者没有显著变化。此外，在TD中，腿肽水平可能直接由TSH 和 T3 水平调节，独立于BMI。

试验注册： CRD42024561055.

关键词： 腿肽；荟萃分析；甲状腺功能障碍；甲状腺激素。

© 2025. 作者