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The thickness of the carotid arteries is increased in subclinical hypothyroidism
The background of the study. An
increase in thickness of the intimal and medial layers of the carotid
arteries is a risk factor for arteriosclerosis, including myocardial
infarction and stroke. Hypothyroidism may be a risk factor for arteriosclerosis.
In this study the thickness of the intimal and medial layers of
the carotid arteries was measured in patients with subclinical hypothyroidism
before and during thyroxine therapy.
How the study was done. The study subjects were 45 patients with subclinical hypothyroidism (high serum thyrotropin [TSH] and normal serum free thyroxine concentrations) and 32 normal subjects. The thickness of the intima and media of the common carotid arteries was determined by ultrasonography. The patients with subclinical hypothyroidism were then randomly assigned to receive thyroxine or placebo for 10 months, after which the ultrasound measurements were repeated.
The results of the study. The patients with subclinical hypothyroidism had higher serum TSH concentrations, lower serum free thyroxine concentrations, and higher serum cholesterol concentrations, as compared with the normal subjects. The mean intima–media thickness of the carotid arteries was statistically significantly higher in these patients (0.75 vs. 0.63 mm).
During therapy, the mean carotid intima–media thickness and serum cholesterol concentrations decreased in the patients who were treated with thyroxine, but did not change in the patients in the placebo group.
The conclusions of the study. Carotid intima–media thickness is increased in patients with subclinical hypothyroidism, and it decreases during therapy with thyroxine.
The original article. Monzani F, Caraccio N, Kozakowa M, Dardano A, Vittone F, Virdis A, Taddei S, Palombo C, Ferrannini E. Effect of levothyroxine replacement on lipid profile and intima-media thickness in subclinical hypothyroidism: a double-blind, placebo-controlled study. J Clin Endocrinol Metab 2004;89:2099-106.
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| Thyroid Digest Index | | | July 2004 Thyroid Digest |
