Karar Musab, Eltayeb Eltahir Suzan Mohammed, Mohammed Ibrahim Afra Mubarak, Mohammed Mahmoud Fatima Salah, Mohamed Abdalla Sara Ahmed, Hyder Mohammed Abeer Abdelraouf, Osman Ahmed Wadah Ahmed
General Practice, Hull University Teaching Hospitals NHS Trust, Hull, GBR.
Internal Medicine, Sudan Medical Specialization Board, Khartoum, SDN.
Cureus. 2025 May 20;17(5):e84475. doi: 10.7759/cureus.84475. eCollection 2025 May.
Metabolic syndrome (MetS) and subclinical hypothyroidism (SCH) are prevalent endocrine-metabolic disorders with significant cardiovascular implications. Emerging evidence suggests a bidirectional relationship between these conditions, but findings remain inconsistent across populations. This systematic review synthesizes existing literature to evaluate the association between SCH and MetS, focusing on prevalence, demographic variations, and mechanistic links. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, a comprehensive search was conducted across PubMed, Scopus, Web of Science, and Embase up to April 2025. Twelve observational studies (cross-sectional, cohort, and case-control) were included after screening. Studies were selected based on predefined criteria: adult populations (≥18 years), clear definitions of SCH (elevated thyroid-stimulating hormone (TSH) with normal free thyroxine 4 (FT4)) and MetS (National Cholesterol Education Program Adult Treatment Panel III (NCEP ATP III), International Diabetes Federation (IDF), or Joint Interim criteria). Data were extracted on study characteristics, prevalence rates, and metabolic associations. Quality assessment used the Newcastle-Ottawa Scale. SCH prevalence was significantly higher in MetS patients (range 8.9-37%) as compared to controls, with notable geographic and gender disparities. Key findings included: (1) Strong associations between SCH and central obesity, dyslipidemia, and hypertension; (2) Gender-specific risks, with males showing higher MetS incidence and females exhibiting higher SCH prevalence; (3) Age-related trends, with SCH prevalence increasing with age, though no elevated risk was observed in individuals ≥50 years. Longitudinal data suggested MetS may predict SCH development. This review supports a significant association between SCH and MetS, driven by shared pathways involving lipid metabolism, insulin resistance, and adiposity. Demographic variations underscore the need for tailored screening, particularly in high-risk groups. Standardized diagnostic criteria and prospective studies are warranted to clarify causality and therapeutic implications.
代谢综合征（MetS）和亚临床甲状腺功能减退症（SCH）是常见的内分泌代谢紊乱疾病，对心血管系统有重大影响。新出现的证据表明这两种疾病之间存在双向关系，但不同人群的研究结果仍不一致。本系统综述综合现有文献，以评估SCH与MetS之间的关联，重点关注患病率、人口统计学差异和机制联系。按照系统评价和Meta分析的首选报告项目（PRISMA）指南，截至2025年4月，在PubMed、Scopus、科学网和Embase上进行了全面检索。筛选后纳入了12项观察性研究（横断面研究、队列研究和病例对照研究）。研究根据预先确定的标准进行选择：成年人群（≥18岁），SCH（促甲状腺激素（TSH）升高且游离甲状腺素4（FT4）正常）和MetS（美国国家胆固醇教育计划成人治疗小组第三次报告（NCEP ATP III）、国际糖尿病联盟（IDF）或联合临时标准）的明确定义。提取了有关研究特征、患病率和代谢关联的数据。质量评估采用纽卡斯尔-渥太华量表。与对照组相比，MetS患者的SCH患病率显著更高（范围为8.9%-37%），存在明显的地理和性别差异。主要发现包括：（1）SCH与中心性肥胖、血脂异常和高血压之间存在密切关联；（2）性别特异性风险，男性MetS发病率较高，女性SCH患病率较高；（3）与年龄相关的趋势，SCH患病率随年龄增加而升高，尽管50岁及以上个体未观察到风险升高。纵向数据表明MetS可能预测SCH的发生。本综述支持SCH与MetS之间存在显著关联，这是由涉及脂质代谢、胰岛素抵抗和肥胖的共同途径驱动的。人口统计学差异强调了进行针对性筛查的必要性，特别是在高危人群中。需要标准化的诊断标准和前瞻性研究来阐明因果关系和治疗意义。
