LDL cholesterol
What it measures, and what changes the number.
LDL cholesterol is the cholesterol carried in low density lipoprotein particles, which transport cholesterol from the liver to tissues. The result is the amount of cholesterol within those particles, not the number of particles.
It is part of the standard lipid panel with total cholesterol, HDL cholesterol and triglycerides, and it is often reviewed alongside non-HDL cholesterol and apolipoprotein B, which describe related aspects of the same particles.
Many labs do not measure LDL directly but calculate it from total cholesterol, HDL and triglycerides, most often with the Friedewald equation, so it depends on those results and is sensitive to triglycerides, which rise after eating. For that reason a fasting sample is often requested. Other labs use a direct assay or newer equations, and the method can shift the number. Labs may print it as Colesterol LDL, Colesterol LDL (càlcul Friedewald) or LDL-CHOLESTEROL.
Often read alongside: Total cholesterol, HDL cholesterol, Triglycerides, Non-HDL cholesterol, Apolipoprotein B