Endocrine Abstracts

Introduction: Hypothyroidism is associated with increased risk of atherosclerosis. We assessed both carotid intima media thickness (CIMT), as a marker of atherosclerosis, and endothelial dysfunction in patients with hypothyroidism.

Methods: We included 70 female patients with hypothyroidism (age 18–55 years), 40 patients with overt and 30 patients with subclinical hypothyroidism (SCH). Forty age and sex matched subjects with normal thyroid functions were also included as a control group. CIMT was measured using high-resolution colour-coded Doppler ultrasonography. Endothelial function was assessed by measuring the percent of change in blood flow following heat mediated vasodilation using Laser Doppler flowmetry.

Results: CIMT was significantly higher in patients with overt and subclinical hypothyroidism as compared with the control group (0.7+0.2 and 0.6+0.2 mm respectively vs 0.45+0.07 mm, P< 0.001 for both). The percent of change in blood flow following heat mediated vasodilation was significantly impaired in patients with overt and subclinical hypothyroidism as compared with the control group (327.5+17 and 545+406% respectively vs 897.7+195.4%, P< 0.001 for both). The impairment was more significant in patients with overt hypothyroidism as compared with those with SCH (P=0.014). There was a significant negative correlation between CIMT and the percent of change in blood flow following heat mediated vasodilation in patients with overt and subclinical hypothyroidism (P< 0.001 for both).

Conclusion: CIMT, as a marker of atherosclerosis, is significantly higher in patients with overt and subclinical hypothyroidism compared with normal control subjects. Impairment of endothelial function is a contributing factor to the increased risk of atherosclerosis in both groups of patients.