Холестерол – липопротеины низкой плотности (ЛПНП)

LDL cholesterol (LDL-C) testing helps estimate atherosclerotic cardiovascular disease risk and supports decisions on prevention and treatment. The result guides initiation and adjustment of lifestyle measures and lipid‑lowering therapy and is used to track attainment of LDL‑C goals over time. This assay is also used to evaluate the effect of dietary modification that restricts animal fats and to document lipid changes during pharmacologic treatment. Synonyms such as low-density lipoprotein cholesterol and LDL-C are commonly used in clinical requests and reports.

Cholesterol is an essential lipid alcohol incorporated into cell membranes and serves as a precursor for steroid hormones and bile acids. Because cholesterol is insoluble in water, it circulates in lipoprotein particles composed of apolipoproteins and lipids. Major classes include very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). Excess LDL cholesterol promotes plaque formation in arterial walls, which restricts blood flow and raises the risk of coronary heart disease and ischemic stroke. Hepatic synthesis supplies most cholesterol needs, with additional intake from dietary animal fats; genetic predisposition and high consumption of animal fats can drive LDL-C to pathologic levels. LDL cholesterol is commonly derived from the lipid panel using the Friedewald formula based on total cholesterol, HDL cholesterol, and triglycerides. The calculated value becomes unreliable when triglycerides are markedly elevated (> 10 mmol/L) or following a fatty meal; in such circumstances, LDL-C should be measured directly by an enzymatic photometric method. Testing should be performed when the patient is clinically stable; after an acute illness, myocardial infarction, or surgery, defer lipid measurement for at least 6 weeks. Results may be reported in conventional or SI units. Conversion factors: mmol/L × 38.66 = mg/dL; mmol/L × 0.3866 = g/L; mg/dL × 0.0259 = mmol/L.