LDL Cholesterol

Overview

LDL cholesterol measures the concentration of low-density lipoprotein particles that primarily transport cholesterol from the liver to peripheral tissues. These lipoproteins deliver cholesterol for cell membrane synthesis and hormone production, but excess levels contribute to atherosclerotic plaque formation in arteries. High LDL cholesterol indicates increased cardiovascular risk, while low levels may reflect malnutrition, liver disease, or genetic disorders like hypobetalipoproteinemia. Clinically, LDL cholesterol assessment guides lipid-lowering therapy decisions and cardiovascular disease prevention strategies.

Clinical Use Cases

  • Assessing risk for atherosclerotic cardiovascular disease (ASCVD).
  • Monitoring response to statin or other lipid-lowering therapies.
  • Guiding treatment decisions in primary and secondary prevention of heart disease.
  • Evaluating familial hypercholesterolemia and other dyslipidemias.

Specimen Types

  • Serum.
  • Plasma (EDTA, heparin, or citrate anticoagulated).

Measurement Methods

  • Direct homogeneous enzymatic colorimetric assay.
  • Friedewald calculation (total cholesterol minus HDL minus triglycerides/5).
  • Beta-quantification ultracentrifugation (reference method).
  • Nuclear magnetic resonance (NMR) spectroscopy for lipoprotein particle size.

Test Preparation and Influencing Factors

  • Fasting 9-12 hours required for accurate triglyceride-based calculations.
  • Recent meals, alcohol intake, or acute illness elevate triglycerides and affect calculated LDL.
  • Medications like estrogens, beta-blockers, or fibrates can increase LDL levels.
  • Pregnancy, hypothyroidism, or nephrotic syndrome physiologically raise LDL cholesterol.

Synonyms

  • Low-density lipoprotein cholesterol.
  • “Bad cholesterol.”
  • Calculated LDL-C.
  • Direct LDL-C.

Further Reading