Relationship Between Serum Thyroid-Stimulating Hormone and Lipid Profile Parameters, Including the Lipid Tetrad Index, in Patients with Hypothyroidism

Background: Hypothyroidism is commonly associated with dyslipidaemia and an increased atherogenic lipid burden. Thyroid hormone deficiency may influence total cholesterol, triglycerides, LDL-C, and HDL-C. Composite lipid indices may provide an integrated assessment of lipid-related risk. Material and Methods: This observational cross-sectional study included 300 patients with hypothyroidism. Serum TSH, FT4, total cholesterol, triglycerides, HDL-C, and LDL-C were evaluated. The Lipid Tetrad Index was calculated using the formula: (total cholesterol × triglycerides × LDL-C)/HDL-C. Correlation analysis was performed to evaluate the relationship between serum TSH and lipid parameters. Results: The mean serum TSH concentration was 9.34 ± 5.35 mIU/L, while the mean Lipid Tetrad Index was 4.17 ± 1.48. Serum TSH showed statistically significant positive correlations with total cholesterol (r = 0.320, p <0.001), triglycerides (r = 0.254, p <0.001), LDL-C (r = 0.288, p <0.001), and Lipid Tetrad Index (r = 0.117, p = 0.043). No statistically significant correlation was observed between serum TSH and HDL-C (r = 0.052, p = 0.368). Conclusion: Increasing serum TSH concentrations were associated with adverse changes in conventional lipid parameters and a higher Lipid Tetrad Index. Comprehensive lipid evaluation may therefore be important in patients with hypothyroidism.

Keywords: Hypothyroidism; thyroid-stimulating hormone; dyslipidaemia; cholesterol; triglycerides; Lipid Tetrad Index.