Cholesterol circulates through the blood bound to transport proteins (apolipoprotein). It is the nature of this apolipoprotein that determines the fate of cholesterol: either its elimination via HDL cholesterol (apolipoprotein A) or its preservation and contribution to the development of cardiovascular disease (apolipoprotein B and non-HDL cholesterol). Apolipoprotein B (Apo B) levels are the most reliable marker for the development of a CVD because it represents all forms of “dangerous” cholesterol (LDL, IDL, VLDL, etc.) and allows for the detection of a particularly dangerous form of bad cholesterol associated with small, high-density particles.
Levels of apolipoprotein B must be interpreted while taking into account the risk of developing a CVD within 10 years following the test (Framingham risk), which is a calculation that includes age, sex, smoking, treated or untreated hypertension and the presence of diabetes in addition to HDL cholesterol levels and total cholesterol. The higher the Framingham risk, the lower the levels of apolipoprotein B should be. The Canadian Cardiovascular Society recommends bringing apolipoprotein B levels down to less than 0.8 grams per litre (g/L) in all individuals with a Framingham risk higher than 20% (elevated risk) and those with a risk between 10 and 20% (intermediate risk) the moment their levels of apolipoprotein B exceeds 1.2 g/L.