Apolipoprotein B-(Apo-B)

What is the Apolipoprotein B test all about?

This is a diagnostic blood evaluation conducted to measure the levels of a type of cholesterol known as Apolipoprotein B-100 (ApoB) in the blood. Low-density lipoproteins (LDL) or otherwise named as the cholesterol which is bad for the heart contains Apo-B as the main protein. High levels of LDL can cause damage to arteries and the heart. Therefore, the Apolipoprotein-B test helps your healthcare provider evaluate your risk of cardiovascular disease.

What is Apolipoprotein B-(Apo-B)?

Lipoproteins consist of proteins called apolipoprotein, cholesterol, phospholipids, and triglycerides. Lipoproteins are particles that convey cholesterol and triglycerides in the blood. Lipoproteins are different due to the concentration of components. Apo-B plays a significant role among the atherogenic lipoprotein particles.

Apo-B 48 and Apo-B 100 are the two main forms of Apo-B.  While mainly the small intestine forms Apo-B 48, Apo-B 100 forms part of the lipoproteins synthesized by the liver. It is present in LDL, IDL, VLDL, LP particles and in chylomicrons. These particles are atherogenic and contain a single Apo-B molecule.

Apo-B 100 significantly influences atherosclerosis and cardiovascular risk, therefore during lipoprotein tests, the levels of Apo-B 100 is more relevant. Many insights have revealed that Apo-B may be a better indicator of cardiovascular risk as compared to LDL-C.  It is also possible to have a normal or low level of LDFL-C, still, the Apo-B level in the blood can be higher which predicts risk of cardiovascular disease.

Is the Apo-B test referred to by other names?

Apolipoprotein-B, Apo-B100, Apolipoprotein (B), Apo-B, are some of the other names that refer to this blood test.

Why should I undergo this test?

If you have already suffered a heart attack or have had heart problems, your healthcare provider will recommend this test. In addition, if you have a genetic predisposition to heart ailments, then this test helps ascertain the imminent risk of heart problems.
If your triglyceride, cholesterol and fat levels are high, you will need to undergo the Apo-B test.  Further, if you are already undergoing treatment to lower fat levels, this test helps evaluate the efficacy of treatment. This test is also performed to assist in the diagnosis of a rare genetic problem known as Apolipoprotein-B (Apo-B) deficiency.

Do I need to undergo more blood tests along with this test?

You may be also be asked to undergo a blood test to examine total cholesterol. This is called the lipid profile test that reveals the levels of HDL, LDL cholesterol and triglycerides in the blood. Your healthcare practitioner is in a better position to assess your heart health with these readings.

Additionally, your health care provider may want to see your scores for both Apo-A1 and Apo-B to ascertain the ratio between these two proteins. The ratio is extremely crucial to gauge the risk of cardiovascular disease, very much like the ratio between total cholesterol level and HDL.

Is there any prior preparation required before the Apo-B test?

There is no special preparation required before the Apo-B test. What is crucial however is that you openly discuss with your healthcare provider about your medical history. This should include all the medicines that form part of your daily intake, supplements, and vitamins. If you are taking any illicit drugs or herbs, make sure you inform your doctor about this.

Do I need to fast before this test?

Your healthcare provider may advise you to stop intake of solids and liquids except water for 9 to 12 hours prior to the test. You may also need to check if you should stop taking any medicines hours before the test is performed.

Can the Apo-B test take place at the Doctor’s Office?

This test need is to be performed in a laboratory, as it needs specialized equipment. In addition, not every laboratory conducts these tests. Therefore, your blood sample is sent to a specialized lab that conducts these tests.

How is the Apo-B test performed?

The Apo-B test requires a blood sample for evaluation. The laboratory technician follows a simple procedure to draw a sample of blood from your vein.

– First, an elastic band is tied around the site on your hand or forearm. This helps locate the vein that swells up with blood after a band is tied close to it.

– The next step is to insert a needle in the vein. The required sample of blood is drawn out into the tube attached to the needle.

– A cotton swab or gauze is placed at the site where blood was drawn to prevent bleeding and bruising.

– The blood sample is sent to the laboratory for testing.

– This is a very simple procedure with a low risk of any complications.

However, in rare cases, patients do experience bruising, infection, bleeding or lightheadedness.  Usually, recovery is quick and in a few hours, patients are back to normal.

Are there any factors that may influence my test results?

If your diet is high in fat, this will negatively affect your test results. If you are on cholesterol-lowering drugs, the test results will appear normal.

For instance, the class of drugs such as diuretics, beta-blockers, androgens, progestins can influence results of this blood examination. Levels of Apo-B can be abnormal in the presence of some underlying medical conditions. Some of the medical conditions that can alter test results are as follows:

– Diabetes
– Nephrotic syndrome
– Hypothyroidism
– Pregnancy

Apo-B levels may also be low due to the presence of any condition that affects lipoprotein production or affects its synthesis in the liver. The presence of following conditions can cause levels of Apo-B to be low in the blood:

– Reye syndrome
– Cirrhosis
– Severe illness
– Weight loss
– Malnutrition
– Hyperthyroidism
– Major surgery

The intake of certain drugs can also cause low Apo-B levels. Some of the drugs are niacin, estrogen, lovastatin, and thyroxine.

How long does it take to get the Apo-B test results?

Most laboratories are able to process the test results of Apo-B in 36 to 48 hours following the test, although it can extend depending on the laboratories.

What do my test results mean?

The test results are dependent on several factors like the method used for testing, medical history, gender, age. The results are compared against the reference range scores and your healthcare provider will be able to interpret the results keeping your health background in mind.

What is the normal reference range for Apo-B?

Reference test results are given in milligrams per deciliter (mg/dL).
The normal range for Apo-B test results is 40-125 mg/dL.

What do the test results mean?

Increased levels of Apo-B may mean that you stand a high risk of suffering from cardiovascular disease.

Normal levels of Apo B-100 in adults are less than 100 mg/dL. Your risk is high if you have an Apo-B result greater than 120 mg/dL.

Those that carry a low or moderate risk are advised to ensure their Apo-B levels are below 100 mg/dL.

Those categorized as high-risk individuals should ensure their Apo-B levels are below 80 mg/dL

What is the cost of the Apolipoprotein-B test in India?

The estimated price of the Apolipoprotein-B test is about Rs 500, although the cost can vary across locations and facilities.

Is it possible to lower my Apo-B levels?

Doctors’ advice dietary modification to lower Apo-B levels. Statins or cholesterol-lowering drugs are also prescribed to normalize the Apo-B levels. Lowering the intake of cholesterol and saturated fats while increasing the amount of mono-and polyunsaturated (omega-3) fatty acids, fiber, and green leafy vegetables can help lower Apo-B levels. A body of research has also pointed towards the advantages of reduced carbohydrate intake in lowering Apo-B levels. Lifestyle changes that include regular physical activity are known to influence Apo-B levels positively, especially the Apo-B/Apo-A1 ratio.