Abstract
The purpose of this meta-analysis was to determine whether patients with
subclinical hypothyroidism (SCH) have impaired endothelial function, which
is assessed by carotid intima-media thickness (C-IMT) and flow-mediated
dilatation (FMD) of brachial artery. PubMed, Embase and Cochrane Library
databases and the key studies references were searched in our study, prior
to July 2017 for all language articles about FMD or C-IMT in SCH and
euthyroid subjects. Two authors screened documents and extracted data by
pre-established standard independently. The pooled estimate for continuous
data was calculated using random-effects models. Statistical heterogeneity
was evaluated using I2 statistics. Subgroup analyses were
conducted to assess the robustness of the meta-analysis. Publication bias
was examined with funnel plot analysis and Egger’s test. In this
meta-analysis, 10 studies with 760 subjects are related to FMD with SCH and
23 studies with 1521 subjects are related to C-IMT with SCH. The pooled
estimate of the weighted mean difference (WMD) has revealed that SCH
correlated with increased C-IMT [WMD 0.069 mm; 95% CI
(0.042, 0.095); p<0.001] and decreased FMD [WMD
−1.848%; 95% CI (−2.298, −1.399);
p<0.001] with high heterogeneity. Compared with EU controls,
SCH was also associated with an increased diastolic blood pressure (DBP),
systolic blood pressure (SBP), triglyceride (TG), total cholesterol (TC)
levels, and low density lipoprotein cholesterol (LDL-C). This meta-analysis
demonstrates that SCH is associated with endothelial dysfunction, which may
relate with increased thyroid-stimulating hormone (TSH). Hypertension and
dyslipidemia may play a crucial part in the development of endothelial
dysfunction.
Key words
endothelial function - subclinical hypothyroidism - meta-analysis
