Atherogenic Plasma Index or Non-High-Density Lipoproteins as Markers Best Reflecting Age-Related High Concentrations of Small Dense Low-Density Lipoproteins

The study aimed to assess the strength of the relationships between small dense low-density lipoproteins (sdLDL) and other parameters describing metabolic disorders and determine which of the lipid profile parameters can be used as markers of increased sdLDL concentration. The proposed model of sdLDL (examined by heparin–magnesium precipitation method) as a function of lipid parameters and atherogenic plasma indexes non-high-dense lipoproteins (non-HDL) and total cholesterol to high-dense lipoprotein ratio (TC/HDL), Atherogenic plasma index (API) is based on data from 485 participants divided into two age groups, <35≥ years. In multiple linear regression, sdLDL concentration was associated with the concentration of non-HDL-C (p = 0.043) and API value (p < 0.001) in participants <35 years, and with non-HDL-C (p < 0.001) and triglycerides (p = 0.020) concentration ≥35 years. The presence of abnormal values of API in participants <35 years and non-HDL-C in participants ≥35 years is a significant factor increasing the chances of the highest sdLDL (≥1.03 mmol/L) corresponding to Q4 in people without metabolic disorders. Different lipid parameters and atherogenicity indexes are associated with a high concentration of sdLDL depending on the age group. Abnormal API <35 years and non-HDL ≥35 years are associated with the highest sdLDL values and may be an indication for further specialist diagnosis of cardiovascular disease risk factors.