- Apolipoprotein B (apoB) levels are used to evaluate the risk for cardiovascular disease.
- LDL and its major protein, apolipoprotein B, play an essential role in lipid transport and metabolism.
- ApoB levels are higher in males than in females and tend to increase with age.
- ApoB plays a central role in carrying cholesterol and triglycerides from the liver and gut to utilization and storage sites.
- Incontestable data support the concept that apoB is a better tool to assess cardiovascular disease than LDL-C and non-DHL-C.
Apolipoprotein B (apoB) is a structural protein that constitutes a major component of the very-low-density lipoprotein (VLDL), the intermediate-density lipoprotein (IDL), and the low-density lipoprotein (LDL). Each of these lipoprotein particles carries one apoB molecule; as a result, the total serum apoB level corresponds to the total number of VLDL, IDL, and LDL particles.
Because VLDL, IDL, and LDL are considered atherogenic, the apoB level should reflect the atherogenic potential of these lipoproteins.
Cardiovascular risk is associated more with the number and size of circulating atherogenic particles than with the concentration of cholesterol in these particles.
ApoB is not equivalent to non-LDL-C, because the latter reflects the cholesterol content of all atherogenic lipoproteins rather than the total number of circulating atherogenic particles.
ApoB seems to be a very important parameter in assessing cardiovascular risk in the setting of diabetes and metabolic syndrome, since patients with these conditions tend to have small, dense LDL particles with relatively normal LDL-C but high apoB levels.
Apo B levels may be decreased with any condition that affects lipoprotein production or affects its synthesis and packaging in the liver. Lower levels are seen with secondary causes such as:
- Use of drugs such as: estrogen (in post-menopausal women), lovastatin, simvastatin, niacin, and thyroxine
- Reye syndrome
- Weight reduction
- Severe illness
Elevated levels of apo B correspond to elevated levels of LDL-C and to non-HDL-C and are associated with an increased risk of cardiovascular disease (CVD).
Elevations may be due to a high-fat diet and/or decreased clearing of LDL from the blood.
Some genetic disorders are the direct (primary) cause of abnormal levels of apo B. For example, familial combined hyperlipidemia is an inherited disorder causing high blood levels of cholesterol and triglycerides. Abetalipoproteinemia, also called Apolipoprotein B deficiency or Bassen-Kornzweig syndrome, is a very rare genetic condition that can cause abnormally low levels of apo B. For more on some of these disorders, see the Related Content section.
Abnormal levels of apo B can also be caused by underlying conditions or other factors (secondary causes). Increased levels of apo B are seen, for example, in:
- Use of drugs such as: androgens, beta blockers, diuretics, progestins (synthetic progesterones)
- Nephrotic syndrome (a kidney disease)
- Pregnancy (levels increase temporarily and decrease again after delivery)
Potential treatment options:
Please consult your doctor before starting a treatment plan.
- Consuming less dietary fat and cholesterol and many more fiber-rich, whole plant foods will greatly reduce the amount of chylomicrons and their atherogenic, apoB-48-containing lipoproteins in the blood.
- Physical exercise can reduce the atherogenic burden as experienced by the reduction in apoB or apoB/apoA-I levels [L]
Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.
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