Background: The relationship between TSH and the lipid profile is contradictory because few studies have excluded the potential influence of the thyroid hormones (TH). The aim of the present study was to evaluate the relationship between serum TSH levels and the lipid profile independent of TH.
Methods: 1302 CHD patients diagnosed by coronary angiography were retrospectively studied. The prevalence and distribution of thyroid dysfunction were analyzed first. To assess the impact of TSH on serum lipids, Pearson's correlation analysis was performed after adjustments for classic factors and TH. To calculate the extent of the effect of TSH on the serum cholesterol level, the partial least squares method and additional statistical methods were used.
Results: After the exclusions, a total of 568 patients (270 males and 298 females with a mean age of 63.56 ± 11.376 years) were selected. The prevalence of thyroid dysfunction among the patients was 18.66%, and the prevalence of hypothyroidism (15.32%) was higher than that of hyperthyroidism (3.34%). Even after adjusting for confounding factors, such as sex, age, smoking status, fasting plasma glucose levels and TH, a significant positive impact of TSH on the serum total cholesterol (TC) level was revealed (r = 0.095, p = 0.036). Each 1 mIU/L increase in the TSH level might be linked to a 0.015580712 mmol/L elevation of the serum TC value.
Conclusions: TSH can increase the TC level in CHD patients independent of TH. The present study suggests a potential physiological role of TSH and the importance of maintaining an appropriate TSH level in CHD patients.