LDL cholesterol represents the level of cholesterol in the blood that is considered “bad cholesterol” and that contributes to the risk of developing cardiovascular disease (CVD). The LDL cholesterol fraction is calculated from the levels of total cholesterol, HDL cholesterol and triglycerides. This calculation is skewed when triglyceride levels are greater than 4 millimoles per litre (mmol/L). In these situations, it is preferable to use non-HDL cholesterol or apolipoprotein B results (see those results).
LDL cholesterol levels must be interpreted in light of the risk of developing CVD within 10 years following the test (Framingham risk), a calculation that factors in age, sex, smoking, treated or untreated hypertension, and the presence of diabetes in addition to HDL cholesterol and total cholesterol levels. The higher the Framingham risk, the lower the level of desirable LDL cholesterol should be. The Canadian Cardiovascular Society recommends lowering LDL cholesterol levels to less than 2.0 millimoles per litre (mmol/L) in all individuals with a Framingham risk above 20% (high risk) and in individuals with a risk between 10% and 20% (intermediate risk) as soon as their LDL cholesterol levels exceed 3.5 mmol/L.