Atherogenic Index of Plasma and Castelli Risk Indices as Useful Biochemical Markers in the Assessment of Cardiovascular Risk in Subclinical Hypothyroidism

Background and Objectives: Subclinical hypothyroidism (SCH) is one of the most common endocrine disorders characterized by the elevated levels of serum thyroid-stimulating hormone (TSH) in the presence of normal T4 and T3 levels. This study was conducted to estimate the lipid profile and to assess the lipid atherogenic risk in patients with SCH. Materials and Methods: This was a case–control study which included 50 SCH subjects and 50 euthyroid controls. Serum T3, T4, and TSH were estimated by chemiluminescent immunoassay method. Serum lipid profile was estimated using fully automated analyzer. Castelli’s Risk Index (CRI) was calculated from total cholesterol (TC), low-density lipoprotein (LDL), and high-density lipoprotein (HDL) and it is categorized into CRI-I and CRI-II. CRI-I = TC/HDL ratio. CRI-II = LDL/HDL ratio. Atherogenic index of plasma (AIP) is log10 (Triglycerides [TG]/HDL) ratio. Statistical analysis was done using the SPSS. Results and Discussion: Our study showed increased serum TC, TG, CRI, and AIP in SCH patients as compared with controls. TC, TG, CRI1, and AIP were found to be positively correlated with TSH. The positive association of atherogenic indices with SCH indicates a need for regular screening of these patients to enable the early diagnosis and treatment of dyslipidemia. Conclusion: Our results suggest that patients with SCH have high atherogenic risk as indicated by the higher values of CRI and AIP. Hence, CRI and AIP can be used as the predictors of cardiovascular risk in SCH.