Aims: To investigate whether levels of thyroid-stimulating hormone (TSH) within the normal range are associated with an increased risk of new vascular events and mortality in patients with clinical manifest vascular diseases and whether this relation is influenced by adiposity.
Methods and results: Prospective cohort study in 2443 patients (1790 men and 653 women) with clinical manifest vascular disease and TSH levels in the normal range. Median follow up was 2.7 (interquartile range 1.4-3.9) years. Clinical endpoints of interest were: myocardial infarction, stroke, vascular death, and all-cause mortality. In patients with manifest vascular disease, the prevalence of (subclinical) hypothyroidism was 5.7%, while 3.6% had (subclinical) hyperthyroidism. An increase in 1 unit of TSH was associated with a 33% higher risk (HR 1.33; 95% CI 1.03-1.73) for the occurrence of myocardial infarction, adjusted for age, gender, renal function, and smoking. In patients with a body mass index (BMI) below the median of 26.7 kg/m(2) the HR per unit TSH for myocardial infarction was 1.55 (95% CI 1.08-2.21) compared to 1.18 (95% CI 0.81-1.71) in patients with a BMI ≥26.7 kg/m(2). Visceral adipose tissue thickness below the median (≤8.8 cm) was associated with higher HR per unit TSH for myocardial infarction (HR 1.69; 95% CI 1.21-2.35) compared to visceral adipose tissue thickness >8.9 cm (HR 1.00; 95% CI 0.66-1.49). There was no relation between TSH and risk of stroke, vascular death, the combined endpoint, or all-cause mortality.
Conclusion: Higher TSH levels within the normal range are associated with an increased risk of myocardial infarction, in patients with clinical manifest vascular disease. This relation is most prominent in patients without visceral obesity.