Subclinical thyroid dysfunction not associated with new carotid plaques
Sustained subclinical thyroid dysfunction appears to have no effect on the development of carotid plaques and risk of systemic atherosclerosis in healthy individuals, a new study has found.
Among the 21,342 patients with consistent serial thyroid functional tests, 20,927 (mean age 54.1±8.5 years) had euthyroidism, 365 (mean age 57.4±8.5 years) had subclinical hypothyroidism and 50 (mean age 57.4. ±7.5 years) had subclinical hyperthyroidism.
Among the three groups, the prevalence of carotid plaques was greatest in the subclinical hypothyroidism group (55.6 percent). This was followed by the subclinical hyperthyroidism and euthyroidism groups (48.0 and 47.8 percent, respectively).
Posthoc analysis showed that the difference in prevalence between the euthyroidism and subclinical hypothyroidism groups was significant (p=0.006).
However, multivariable analysis showed that thyroid status, measured by free T4 levels, was not significantly associated with the risk of baseline carotid plaques in both euthyroidism (odds ratio [OR], 1.094; 95 percent CI, 0.919 to 1.303; p=0.311) and subclinical hypothyroidism (OR, 0.381; 0.097 to 1.486; p=0.164) groups.
Over a mean follow-up of 6.0 years, free T4 (p=0.135) and serum thyrotropin (TSH; p=0.518) levels, along with thyroid functional status (ie, sustained euthyroidism or subclinical hypothyroidism; p=0.392), had no significant effect on the incidence of carotid plaques over time.
In contrast, traditional cardiovascular risk factors significantly tied to risk of baseline carotid plaque in the euthyroidism and subclinical hypothyroidism groups included age (OR, 1.083; 1.079 to 1.088; p<0.001 and OR, 1.072; 1.041 to 1.104; p<0.001, respectively) and systolic blood pressure (OR, 1.015; 1.011 to 1.018; p<0.001 and OR, 1.017; 1.002 to 1.032; p=0.023, respectively).