Endocrine Abstracts

Controversy remains as to the risk of cardiovascular disease (CHD) associated with subclinical hypothyroidism (SCH). Substantial evidence indicates altered cholesterol and lipoprotein metabolism in SCH when serum TSH is above 10 mUI/l. It is apparent that an enhanced CV risk could apply to these patients, amplified by the co-presence of other risk factors such as endothelial dysfunction and elevated C-reactive protein.

We assessed the association between SCH and CHD. We investigated 69 patients, 35 with SCH and 34 euthyroid subjects, with baseline TSH measurements and 24 months follow-up data to determine whether SCH was associated with coronary heart disease; the prevalence of CHD in subjects with subclinical thyroid dysfunction was evaluated. Subjects with SCH had a significantly higher prevalence of CHD than euthyroid subjects OR, 2.2, 95% CI, 1.2–3.8, TSH:7.0–9.9 mUI/l, P: 0.02; OR, 3.2, 95% CI, 1.8–8.9, TSH over 10 mUI/l, P: 0.01. In multivariate analysis, the risk of CHD was higher among those with high TSH levels (TSH: 7.0–9.9 mUI/l, HR, 2.49, 95% CI, 1.17–5.3, P: 0.02, TSH over 10 mUI/l, HR, 3.27, 95% CI, 1.59–6.34, P<0.01). Among the 56 participants without CHD at baseline, the HR for incident CHD events was higher among those with TSH over 7.0 mUI/l (TSH: 7.0–9.9 mUI/l, HR, 1.6, 95% CI, 1.0–2.6, P: 0.04; TSH over 10 mUI/l, HT, 2.5, 95% CI, 1.3–5.3, P<0.01). The increased risk of coronary heart disease events remained significant after adjustment for standard cardiovascular risk factors. Subclincal hypothyroidism is associated with an increased risk of CHD events among adults with a TSH level of 7.0 mUI/l or greater. Subclinical hypothyroidism may be an independent risk factor for coronary heart disease but investigation is warranted to assess whether SCH causes/worsens CHD.