The test for ApoE is may be used in combination with other lipid tests that evaluate risk for CVD, such as cholesterol levels and lipoprotein electrophoresis. It may be used to check for and help to diagnose a genetic component to a lipid abnormality. Testing for ApoE may sometimes be ordered to help guide lipid treatment. In cases of high cholesterol and triglyceride levels, statins are usually considered the treatment of choice to decrease the risk of developing CVD. However, there is a wide variability in the response to these lipid-lowering drugs that is in part influenced by the Apo E genotype. Though appropriately responsive to a low fat diet, people with ApoE e4 may be less likely than those with ApoE e2 to respond to statins by decreasing their levels of LDL-C and may require adjustments to their treatment plans
In Alzheimer's Disease - ApoE genotyping is also sometimes used as an adjunct test to help in the diagnosis of probable late onset Alzheimer's disease (AD) in symptomatic adults. It is called susceptibility or risk factor testing because it indicates whether there is an increased risk of AD but is not specifically diagnostic of AD. If a patient has dementia, the presence of ApoE4 may increase the likelihood that the dementia is due to AD, but does not prove that it is.