Evaluation of Dyslipidemia, Lipid Ratios and Atherogenic Index as Cardiovascular Risk Factors in Overt and Subclinical Hypothyroid Patients

Abstract

Background: Thyroid disorders are known to cause metabolic disturbances. Dyslipidemia, one of the important modifiable cardiovascular risk factors is known in patients with overt hypothyroidism (OHT) and is also reported in sub clinical hypothyroidism (SHT). Aims: To evaluate dyslipidemia, lipid ratios and atherogenic index in patients with OHT and SHT in comparison with healthy controls and between the hypothyroid patients. Material and Methods: The study included 36 patients with OHT, 36 patients with SHT and 39 euthyroid controls. OHT was diagnosed with thyroid stimulating hormone (TSH) level of >15 mU/L and thyroxine (T4) <55µg/L, while SHT was diagnosed with TSH levels between 5-15 mU/L and T4 levels between 55-135µg/L. T3, T4, TSH, total cholesterol (TC), triglycerides (TG) and high-density lipoprotein cholesterol (HDL) were estimated. Low-density lipoprotein cholesterol (LDL-C), very low-density lipoprotein cholesterol (VLDL–C), non-HDL-cholesterol (non HDL-C), lipid ratios and atherogenic index (AI) was calculated. Statistical Analysis: Differences between groups were tested with analysis of variance (ANOVA). Spearman correlation analysis was performed to study the association between parameters. Statistical analysis was performed using SPSS for Windows 11.5 program. Statistical significance was considered at p<0.05. Results: TC, TG, LDL-C, VLDL-C were significantly elevated in patients with OHT, compared to SHT patients and controls (p<0.01). Patients with SHT had significantly higher LDL-C than controls (p<0.01). HDL-C was significantly lower in OHT and SHT patients compared to controls (p<0.01). Non HDL-C, lipid ratios including TC/ HDL- C, TG/HDL-C, LDL-C/ HDL-C and AI were significantly higher in OHT and SHT patients than controls (p<0.01). In patients with OHT, T4 correlated with TC (r = - 0.37, p < 0.05) and non HDL-C (r=- 0.34, p<0.05); TSH correlated with TC (r=0.42, p<0.05) and LDL-C (r=0.44, p<0.05). No correlation for T4 or TSH with any of the lipid parameters was observed in patients with SHT. Conclusion: Dyslipidemia was observed in patients with OHT and also in SHT. Evaluation of lipid parameters including non HDL-C, lipid ratios and AI helps in better identification of cardiovascular risk, especially in patients with SHT, who were found to have normal TC, TG and VLDL-C levels.

Keywords

• atherogenic risk
• dyslipidemia
• hypothyroidism
• lipid ratios
• atherogenic index