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ApoB/ApoA1: The Test

Measuring ApoB and ApoA1 can be performed using standard immunoassay techniques. Nephelometry is popular, as are ELISA-based methods that are performed on automated chemistry analyzer platforms.

The power of the ApoB/ApoA1 ratio as a cardiovascular risk marker is getting widespread attention. An individual with seemingly normal LDL-C may in fact have high ApoB concentrations. When this individual has his or her ApoB/ApoA1 ratio calculated, the risk is evident. Studies have also shown that patients with metabolic syndrome and type-2 diabetes can also easily be identified with the ApoB/ApoA1 ratio, whereas these patients cannot always be identified by measuring LDL-C and HDL-C.

In 2004, the global INTERHEART study of risk factors for acute myocardial infarction concluded that the ApoB/ApoA1 ratio was the most important risk factor in all geographic regions. The ApoB/ApoA1 ratio is easy to use because the risk is integrated into a single number that indicates the balance between atherogenic and antiatherogenic particles.

There have been many studies concerning the predictive power of the ApoB/ApoA1 ratio. One study, which involved thousands of patients who were followed for an average of 10 years, showed that the ApoB/ApoA1 ratio was a strong predictor of stroke in addition to other cardiovascular events. Due to the evidence presented in studies like these, the National Academy of Clinical Biochemistry (NACB) has recommended that the ApoB/ApoA1 ratio be used as an alternative to the usual total cholesterol (TC)/HDL cholesterol ratio when determining lipoprotein-related risk for cardiovascular disease. Some believe that ApoB/ApoA1 testing will eventually replace traditional LDL-C and HDL-C measurements.