Association between hypothyroidism and carotid intima-media thickness

Objective Hypothyroidism has been associated with increased cardiovascular risk, but its relationship with carotid intima-media thickness remains incompletely defined, particularly when overt and subclinical disease are considered separately. This systematic review and meta-analysis evaluated whether hypothyroidism is associated with increased carotid intima-media thickness compared with euthyroid status. Methods A systematic literature search was conducted in PubMed, Scopus, and Web of Science to identify studies published between January 2014 and April 2026 that reported carotid intima-media thickness in patients with overt or subclinical hypothyroidism and euthyroid controls. Eligible studies were qualitatively summarized and quantitatively pooled using random-effects models. Effect estimates were expressed as mean differences with 95% confidence intervals. Subgroup analyses were performed according to thyroid dysfunction severity. Results Sixteen studies, comprising 1,370 patients with hypothyroidism and 5,563 euthyroid controls, were included in the quantitative meta-analysis. Overall, hypothyroidism was associated with significantly increased carotid intima-media thickness compared with euthyroid controls (mean difference 0.10 millimetres, 95% confidence interval 0.04 to 0.16). Subgroup analyses showed increased carotid intima-media thickness in both subclinical hypothyroidism and overt hypothyroidism, with a larger effect in overt disease; the between-subgroup difference was statistically significant (p = 0.047). Sensitivity analyses confirmed the stability of the pooled estimate. Conclusions Hypothyroidism is associated with a measurable increase in carotid intima-media thickness, supporting a link between thyroid hormone deficiency and early vascular remodelling. The stronger association observed in overt hypothyroidism suggests a relationship between disease severity and vascular burden.