Large and medium sized artery abnormalities in untreated and treated hypothyroidism

BACKGROUND: Hypothyroidism is frequently accompanied by cardiac dysfunction, increased vascular resistance and a greater prevalence of hypertension. Whether this condition is also accompanied by alterations of large artery function and structure is not known, however. PATIENTS AND METHODS: We investigated radial artery compliance and wall thickness as well as carotid artery compliance in 11 normotensive recently diagnosed and never treated hypothyroid patients. Fifteen euthyroid healthy age- and sex-matched subjects served as controls. No subject had evidence of large artery atherosclerotic lesions. Carotid artery diameter was evaluated continuously by a B-M mode device and carotid compliance obtained by the Reneman formula. Radial artery diameter and wall thickness were continuously acquired over the systodiastolic blood pressure range (beat-to-beat finger measurement) by an echo-tracking device, and compliance (Langewouters formula) was expressed as the integral of the area under the compliance/blood pressure curve normalized for pulse pressure. RESULTS: Patients with hypothyroidism showed greater radial wall thickness (+109%, P < 0.01) and compliance (+58%, P < 0.03) than controls. Carotid artery compliance was not different in the two groups. In 10 hypothyroid patients L- tiroxine therapy for 9.0 +/- 2.3 months did not change carotid artery function but markedly reduced radial artery wall thickness (-36%, P < 0.05) and compliance (-20%, P < 0.05). CONCLUSIONS: Hypothyroidism is associated with early arterial structural and functional alterations, which involve more muscular than elastic arteries. These alterations, however, are reversible by hormonal replacement therapy.