The apolipoprotéines (or apoproteins) are proteins made by the liver which are involved in the transport of lipids (cholesterol, triglycerides, phospholipids) in the blood. In fact, lipids are insoluble in serum and can only circulate therein in association with lipoproteins (kinds of “vesicles” or micelles). These lipoproteins have a protein part: the apolipoproteins.

These are made up of several assembled proteins, and there is a wide variety of them: in total, ten classes and subclasses are listed.

The blood test mainly concerns apolipoproteins B (which are associated with LDL cholesterol) and apolipoproteins A1 (HDL cholesterol).

The dosage of apolipoproteins is sometimes used in addition to the lipid balance, that is to say the measurement of cholesterol and blood lipids.

It helps to assess an individual’s cardiovascular risk: it increases when the level of apolipoprotein A1 decreases and the level of apolipoprotein B increases.

Indeed, the concentration of apolipoproteins indirectly reflects the concentration of “good” and “bad” cholesterol in the blood.

According to the High Authority for Health in France:

– the dosage of apolipoprotein A1 is to be carried out when the concentration of HDL-cholesterol is less than 0,35 g / l or greater than 0,80 g / L

– the dosage of apolipoprotein B is to be carried out when the concentration of triglycerides is greater than 3,4 g /

The blood test consists of a sample of venous blood, usually at the fold of the elbow. The sample is taken with an empty stomach. Your doctor may ask you to first stop taking certain medicines which can affect the concentration of apolipoproteins in the blood (especially corticosteroids, diuretics, beta blockers, etc.).

The normal concentration of apolipoprotein A1 (or Apo A1) is between 1,10 to 1,80 g / l (grams per liter), and that of apolipoprotein B (or Apo B) is between 0,50 to 1,50 , XNUMX g / l. However, these usual values ​​vary from one laboratory to another and according to the sources.

A drop in the blood level of Apo A1 (below 1,1 or 1,2 g / l) is a sign of the risk of atherosclerosis, that is to say the deposit of “plaques” in the vessels. likely to clog them.

Its elevation, on the other hand, is a sign of good cholesterol elimination and therefore protection against cardiovascular disease.

An increase in the concentration of ApoB (rate greater than approximately 1,3 g / l) reflects an increase in cardiovascular risk.