BACKGROUND: Recently, subclinical
hypothyroidism has been associated with increased
carotid intima-media thickness , but it is controversial.
OBJECTIVE: To assess whether
carotid intima-media thickness in
patients with subclinical
hypothyroidism differs from that in euthyroid subjects.
METHODS: We searched published studies concerning the
carotid intima-media thickness of
patients with subclinical
hypothyroidism in comparison with euthyroid subjects. Then, we evaluated each potential study for eligibility, assessed the methodological quality, and extracted the data for a
Meta-analysis .
RESULTS: Eight observational studies with 3 602 cases met the eligibility criteria. In
patients with subclinical
hypothyroidism , the pooled estimate of the weighted mean difference (WMD) of increased
carotid intima-media thickness was 0.056 [95%CI (0.020, 0.092)].
Sensitivity analysis using a pooled result of the seven higher-quality studies demonstrated higher
carotid intima-media thickness level in
patients with subclinical
hypothyroidism than in euthyroid subjects [WMD=0.064, 95%CI(0.024, 0.105)]. In a subgroup
analysis , subclinical
hypothyroidism was even more significantly associated with the
carotid intima-media thickness in
patients with a mean
thyrotropin level > 10.0 mU/L [WMD=0.082, 95%CI (0.049, 0.116)]. Subclinical
hypothyroidism was also associated with a significant increase in systolic
blood pressure ,
triglyceride levels, total
cholesterol levels,
low-density lipoprotein levels and with a decrease in
fasting plasma glucose . This
meta-analysis indicates that subclinical
hypothyroidism is associated with an increased carotid
carotid intima-media thickness , which may be due to elevated
thyrotropin ,
dyslipidemia and
hypertension . Despite the obvious
individual differences , a prospective large-sample study is necessary to further assess the conclusions of this
observation .