Background:
Research shows that subclinical hypothyroidism (SCH) is related to increased carotid intima media thickness (CIMT), a surrogate marker of stroke and subclinical cardiovascular disease (CVD). It is controversial whether SCH should be treated or not to reduce risk of stroke and CVD morbidity and mortality. The aim of this meta-analysis was to determine whether SCH is associated with an increase in CIMT as compared to Euthyroidism (EU) and whether thyroxin therapy in SCH can reverse the change in CIMT.
Methods:
Two independent reviewers did an extensive database search up to December 2016. Total of 12 randomized clinical trials discussed effect of thyroxin treatment on CIMT values at pre-and-post treatment in SCH subjects.
Results:
CIMT was significantly higher among SCH (n=280) as compared to EU controls (n=263) at baseline, pooled standardized mean difference (SMD) of CIMT was 0.44 mm [95%CI 0.14, 0.74], SE=0.15; p=0.004 with heterogeneity I
2
= 65%. After treatment with thyroxin in SCH subjects (n=314), there was a statistically significant decrease in CIMT from pre-to-post treatment, pooled SMD of CIMT decrease was [SMD -0.32; 95%CI (-0.47, -0.16), SE=0.08; p<0.0001, with heterogeneity I
2
= 2%], and was no longer different from EU controls [SMD 0.13 mm; 95% CI (-0.04, 0.30); p= 0.14; I
2
= 27%]. The total cholesterol, triglycerides, and low density lipoprotein were higher in SCH as compared to EU controls and decreased significantly after treatment with thyroxin.
Conclusion:
This meta-analysis shows that thyroxin therapy in SCH subjects significantly decreases CIMT and improves lipid profile, modifiable risk factors for stroke and CVD. Thyroid hormone replacement in SCH subjects might have a role in slowing down or preventing progression of atherosclerosis.
Association of Exposure to Particular Matter and Carotid Intima-Media Thickness: A Systematic Review and Meta-Analysis
