Apolipoprotein E or apo E is the most important protein found in chylomicrons and very low density lipoproteins, or VLDL cholesterol. This lipoprotein helps the body by removing cholesterol and triglycerides from the blood. It transports them to the liver, where they are destroyed. Testing for Apo E is not generally done and its usefulness is still being researched.
Apo E tests might be ordered along with other lipid tests to check for the risk of cardio vascular diseases such as high cholesterol levels and lipoprotein electrophoresis. This test could also help in the diagnosis of lipid abnormality. Doctors may use this test to help guide lipid treatment. Doctors may also order this test if they suspect type III hyperlipoproteinemia in a person, who exhibits symptoms of this disorder or if a patient’s close family has this disorder. Apo E genotyping is also ordered if a patient has considerably high levels of cholesterol and triglyceride levels that remain unresponsive to changes in diet and exercise. The apolipoprotein E gene increases the risk of developing late-onset of Alzheimer’s disease. Although this test does not specifically diagnose Alzheimer’s disease (AD), ApoE genotyping can indicate susceptibility or increased risk of AD. It is sometimes used as an additional test to diagnose the late inset of AD in adults, who display symptoms of AD.
For the Apolipoprotein E test, a blood sample is taken from the patient’s arm. The doctor or lab technician will wrap a band around the patient’s forearm. This will stop the flow of blood and make the vein below the band to swell, as blood collects in it. This makes it easy to pierce the vein and collect a blood sample. Next the doctor will cleanse the skin at the intended puncture site and use a sterilized needle to puncture the vein. A tube or vial is attached to the needle to collect the blood. After the sample is collected, the needle is gently removed and pressure is applied to the puncture site for a few seconds. A small bandage is then placed on the puncture site, and the sample is sent for testing.
No special preparation is required for this test. Ask your doctor whether you need to fast before taking the test. Ensure that your doctor is aware of all your medications so that he or she can stop or reduce the dosage of any medication that might interfere with test results.