Subclinical hypothyroidism is associated with a low-grade inflammation, increased triglyceride levels and predicts cardiovascular disease in males below 50 years.

OBJECTIVE: Mild thyroid failure is associated with an increased risk for development of atherosclerosis, but whether subclinical hypothyroidism is related to risk for cardiovascular disease is controversial. The purpose of the present study was to examine a possible association between subclinical hypothyroidism and cardiovascular disease.
DESIGN: Cross-sectional study of a general population. PATIENTS: Twelve hundred and twelve subjects, men and women, between 20 and 69 years old without thyroid disease not treated with drugs interfering with thyroid function or analysis of TSH were included. MEASUREMENTS: Clinical signs of cardiovascular disease based on a questionnaire and medical records and laboratory analysis of lipids, atherothrombotic risk markers, C-reactive protein and TSH.
RESULTS: The main findings were a high incidence of subclinical hypothyroidism (19.7%) in a general population. Subclinical hypothyroidism was associated with higher concentrations of triglycerides and C-reactive protein. Below 50 years of age cardiovascular disease was more frequent in males with subclinical hypothyroidism compared to euthyroid males. Subclinical hypothyroidism was a predictor of cardiovascular disease in males below 50 years with an odds ratio of 3.4 (95% confidence interval 1.6-6.8) for developing cardiovascular disease compared to euthyroid age-matched males.
CONCLUSION: Our study demonstrates that patients with subclinical hypothyroidism have increased levels of triglycerides and signs of low-grade inflammation (raised C-reactive protein levels) and that subclinical hypothyroidism might be a risk factor for development of cardiovascular disease in younger males.