Western Blot (HIV Confirmatory Test) Lab Test

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What is the Western Blot HIV Confirmatory Test?

HIV (Human Immunodeficiency Virus) is a virus that destroys or damages the immune system, which then eventually leads to serious infections.

People are infected with this virus generally through unprotected sex with an infected person via semen or vaginal fluid, contact with the blood of a HIV infected person or by infected women to their babies during pregnancy. AIDS (acquired immunodeficiency syndrome) is a result of a HIV infection.

When HIV is suspected, a western blot test is generally administered. Blood is drawn in this test and is checked for HIV antibodies, the presence of which indicates the existence of the HIV virus. The blood sample is separated with an electrical current and is transferred to membrane.

On addition of a particular enzyme, the pattern on the membrane is seen to change and is compared to a standard to check the presence of HIV antibodies. The Western blot test is used along with the ELISA test. The combined tests are 99.9% accurate.

Why Do I Need This Test?

HIV infection, more often than not, goes undetected and without any symptoms in its early stages. Infected people may be subject to colds or flu-like illness that may last up to six weeks. The HIV infection severely damages the immune system which may lead to easily acquired illnesses.

What Other Tests Might I Have Along with This Test?

In general, the Western Blot HIV test is done after the HIV DUO or ELISA test and is just a confirmatory test. The ELISA test screens for the HIV infection, while the Western Blot test checks for HIV antibodies.

What Do My Test Results Mean?

If the test result is positive, HIV infection is confirmed, this nay result in damage of the immune system, which means the body loses its capacity to fight disease and illness. On the other hand, if the test result is negative, other causes for the symptoms experienced, must be tested for.

If the test result is indeterminate it could be due reasons unrelated to HIV exposure. Generally, if such a result occurs, people are advised to repeat the test until a clear result is arrived at.

 

How Is This Test Done?

As with a regular blood test, a health professional will clean the surface of the skin with an antiseptic and will apply pressure to the upper arm which causes the veins to swell. A needle is then inserted into a vein and the blood is drawn and collected in a syringe.

Once the required amount of blood is collected, the needle is removed and the injected area is dressed to stop the bleeding. This procedure takes only a few minutes. The blood then goes through a series of tests to check for the presence of HIV antibodies.

Does This Test Pose Any Risk?

There are some risks associated with this test. Most of the risks are associated with the cleanliness and sterilization of the equipment. If not properly sterilized, infections may be acquired. Another risk may be fainting or feeling lightheaded due to the loss of blood.

In some cases, the blood may also accumulate under the skin and cause lumps or bruises.

What Might Affect My Test Results?

The variables that may affect your test results are your nutritional diet, lifestyle and any other existing medications you're currently on. Doctors should be informed if you're using any supplements or prescription medications before the test is administered.

Sometimes, if exposure to HIV occurred less than 3 months prior to the test, HIV infection may be present but not yet detectable. In cases such as these, the person should be tested 3 months after infection.

Sample Required

The sample required for this test is a blood sample. This sample is collected from a vein, usually in the arm and is collected in a syringe or vial. This is referred to as venepuncture.

How do you understand this result?

The HIV test result could be positive, negative or indeterminate. When positive, the presence of HIV is confirmed and precautions should be taken to make sure that it doesn’t spread. When negative, the person may be clear of HIV virus. When indeterminate, the test is usually administered again, until a clear positive or negative result is obtained.

In todays world, treatments that can slow down the rate at which HIV weakens the immune system exist, but there is no cure for the disease.

How Do I Prepare For The Test?

When it comes to blood tests, there aren’t many precautions you need to take. You may be asked to avoid eating or drinking for up to eight hours before the test is administered.

Depending on what medications you take, your doctor will inform you whether or not you need to avoid them for some time before the test so that your results aren’t affected.

Understanding results of Western Blot (HIV Confirmatory Test)

Reference RangeInterpretation
(HIV1/HIV2):NOT SEENNegative

‘*A Reference range is a set of values which helps the healthcare professional to interpret a medical test. It may vary with age, gender, and other factors. Reference ranges may also vary between labs, in value & units depending on instruments used and method of establishment of reference ranges’

Conclusion

Testing for HIV is the only way to know whether or not you have it. Knowing whether you have HIV or not is important not just for yourself, but for your partners health and can help you be better prepared so as to prevent spreading of the virus.

References

  1. http://www.ncbi.nlm.nih.gov/pmc/articles/PMC119890/
  2. https://stanfordhealthcare.org/medical-conditions/sexual-and-reproductive-health/hiv-aids/diagnosis/western-blot-test.html
  3. https://aidsinfo.nih.gov/understanding-hiv-aids/glossary/751/western-blot
  4. https://wwwn.cdc.gov/nchs/data/nhanes/2011-2012/labmethods/hiv_g_met_eia_wb.pdf
  5. http://www.ucsfbenioffchildrens.org/tests/003538.html
  6. https://medlineplus.gov/ency/article/003538.htm
  7. https://blogs.jwatch.org/hiv-id-observations/index.php/its-time-to-dump-the-hiv-western-blot/2012/09/19/