Lipid metabolism and biomarkers for cardiovascular risk control

What are lipoproteins?

Cholesterol and triglycerides are molecules (lipids) that cannot easily circulate in the bloodstream. In order for cholesterol and triglycerides to travel in the blood, they are often carried by proteins that make cholesterol and triglycerides soluble in the blood. This lipid and protein complex is called a lipoprotein.

When triglycerides and cholesterol are removed from this lipoprotein complex and only the protein remains, this protein component is called apolipoprotein. Different types of apolipoproteins are associated with different lipoproteins.

Apolipoprotein A1

Apolipoprotein A1 is a major component of high density lipoproteins (HDL). HDL-lipoproteins are formed in the liver and small intestine and transport excess cholesterol from extrahepatic tissue and peripheral cells to the liver, thus “clearing” fat from the tissues and slowing the evolution of atherosclerotic plaques.

Apolipoprotein A1 levels increase in liver disease, pregnancy, and as a result of estrogen intake (e.g., oral contraceptives). Apolipoprotein A1 levels decrease in inherited hypo-α-lipoproteinaemia (e.g. Tangier disease), cholestasis, sepsis and atherosclerosis. The liver also synthesizes very low density lipoproteins (VLDL), which contain mainly triglycerides and cholesterol.

Apolipoprotein A1 may reflect particularly well a disturbance in lipid metabolism and the risk of developing atherosclerosis or coronary heart disease, thus providing an excellent complement to the classical HDL/LDL-cholesterol determination. A high apolipoprotein A1 (HDL) level and a low apolipoprotein B (LDL) level correlate best with a low risk for these diseases.

Apolipoprotein B

Apolipoprotein B is the main component of low-density lipoproteins (LDL). About one-third of these LDL particles provide cholesterol to peripheral cells, and the remaining two-thirds are metabolized by the liver. Levels of apolipoprotein B rise during pregnancy, in hypercholesterolaemia, LDL receptor defects, biliary obstruction, type II hyperlipidaemia and nephrotic syndrome. Apolipoprotein B levels decrease during liver disease, α-β lipoproteinemia, sepsis, and with estrogen administration.

The combination of the determination of Apolipoprotein A1 and Apolipoprotein B and the calculation of the Apolipoprotein B/Apolipoprotein A1 ratio indicates the status of lipid metabolism and the risk of developing atherosclerosis and coronary heart disease. Clinical studies have shown that the ApoB/ApoA1 ratio has a significantly higher predictive value for the development of myocardial infarction than other lipoprotein ratios (LDL/HDL; TC/HDL) and have identified it as one of the most accurate indicators of cardiovascular risk. Low values of the ApoB/ApoA1 ratio are associated with low cardiovascular risk, whereas high values of the ratio are associated with high cardiovascular risk.

Lipoprotein(a)

Lipoprotein(a) is a cholesterol-rich lipoprotein that is synthesized in the liver independently of triglycerides and does not depend on environmental factors – diet, physical activity. An elevated level of lipoprotein(a) is considered the most sensitive parameter for the development of coronary heart disease independent of other plasma lipoproteins. The risk of developing coronary heart disease with an elevated lipoprotein(a) level is further increased in the presence of other risk factors, such as high LDL-cholesterol or low HDL-cholesterol levels.

Lp(a) levels are a difficult-to-modify factor in the development of cardiovascular disease because they are not affected by standard therapy for high cholesterol (statins).

hsCRP (High-sensitivity C-reactive protein)

hsCRP is proposed as a method to predict the risk of heart attack or other heart diseases in healthy people. If your hsCRP result is in the upper part of the normal range, it may mean that you are at risk of developing heart disease and other heart conditions. People who look healthy but whose hsCRP results are high , have a 2 to 4 times greater risk of developing clogged arteries.

These parameters should be determined together with total cholesterol, HDL-cholesterol, LDL-cholesterol and triglycerides in the assessment of total atherosclerotic risk.

LIPOPROTEIN PACKAGE – 71 BGN

• Apolipoprotein A1
• Apolipoprotein B
• Lipoprotein(a)
• Total cholesterol
• HDL-cholesterol
• LDL-cholesterol
• VLDL-cholesterol
• Triglycerides
• hsCRP

An additional sampling fee is payable.