Association between serum thyrotropin and high-sensitive CrP as an inflammatory marker of cardiovascular risk

A single measurement of low serum thyrotropin (TSH) in individuals aged 60 years or older is associated with increased mortality from all causes, and in particular mortality due to circulatory and cardiovascular diseases. Our aim was to investigate the association between serum TSH and high sensitive CrP as an inflammatory cardiovascular risk marker. The study population comprised 38 patients (9 men) with overt hyperthyroidism (TSH <0.1mU/l), 40 patients (15 men) with decreased serum TSH levels (TSH 0.1–0.5mU/l), 45 euthyroid patients (21 men), and 18 patients (7 men) with elevated TSH levels (TSH >2.5mU/l). Serum CrP levels were considered as elevated when they belonged to the top quartile of the CrP distribution. The proportion of increased serum CrP among patients with overt hyperthyroidism, with decreased serum TSH, with euthyroidism and with elevated serum TSH was 39.5%, 20.0%, 11.1%, and 38.9%, respectively (p<0.05). After adjustment for age and sex and in comparison to euthyroid patients, a higher risk of increased serum CrP was observed in patients with overt hyperthyroidism (odds ratio 5.30; 95-% confidence interval 1.62–17.36) as well as in patients with elevated serum TSH (odds ratio 5.09; 95-% confidence interval 1.32–19.63). There is a U-shaped association between thyroid function status and inflammatory risk markers such as high sensitive CrP. This correlation may help explain the previously demonstrated association between subclinical hyperthyroidism and vascular mortality.