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What Is the ELISA Test?

Reviewed by Dan Brennan, MD on April 20, 2021

If your doctor suspects you have one of several diseases, they may want to perform an “enzyme-linked immunosorbent assay” test. This is more commonly known as an ELISA test, and it can help to confirm your diagnosis. 

An ELISA test is a blood test that looks for antibodies in your bloodstream. When certain antibodies are present, it’s a sign your immune system is trying to fight off a disease. Here’s how ELISA tests work and what to expect if you need one. 

What Can ELISA Tests Help Diagnose?

An ELISA test can help identify situations that lead your immune system to make antibodies. Certain diseases aren’t easy to identify with other means like swab tests. In these cases, an ELISA blood test can help spot signs of infection or disease in your system. 

A few of the conditions an ELISA test can help identify include:

How Do ELISA Tests Work?

An ELISA test uses specialized enzymes that attach to antibodies in your blood. The test involves mixing a sample of your blood with a known compound on special absorbent plates. Depending on what your doctor is diagnosing, the test can use many different enzymes and identify many different antibodies.

If your blood contains the antibody your doctor is looking for, the enzymes on the plate will attach to it. Positive tests make the plates change color, while negative tests do not. Depending on the change, the lab is able to tell whether you have a certain condition. In some cases, they can even determine how severe the condition is.

What to Expect During an ELISA Test

An ELISA test is quick and easy for you as the patient. Most of the testing process happens in a lab, and you do not need to be present for it. All you need to do is have your blood drawn.

During the test, a healthcare worker will sterilize your inner elbow with an antiseptic wipe. They will also apply a tourniquet to your upper arm in order to make the blood draw site more visible. Then they will place a needle in your arm and pull out a small sample of blood into a vial. This is the sample that will be tested in the lab. 

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Once they have collected enough blood, the healthcare worker will remove the needle and have you put pressure on the blood draw site. This helps the site clot and prevents bleeding. You may experience a small amount of discomfort when the needle is placed and removed or when you put pressure on the site. 

Once you have kept pressure on the site for several minutes, the healthcare worker will confirm that the site is clotted. They may give you an arm wrap and instructions when to remove it. They will also make sure you’re not feeling dizzy or lightheaded. Once you’re feeling comfortable, you’ll be finished and free to leave.

It may take several weeks to get the result from your ELISA test back. Your doctor will notify you about the results and may have you come in to talk about them. 

ELISA tests are usually the first step of the diagnosis process. If an ELISA test comes back positive, your doctor may ask you to take further tests to confirm the diagnosis. If it comes back negative, they may have you repeat the test in a few weeks in case of a false negative result. 

Risks of ELISA Tests

An ELISA test has few risks because the test itself is performed on your blood sample in a lab. The risks come from the process of getting your blood sample drawn. Some potential risks of getting your blood drawn done include:

  • ‌Feeling dizzy or faint
  • ‌Bruising at the site of the blood draw
  • Bleeding from the site of the blood draw
  • ‌Infection in the site of the blood draw

‌Phlebotomists have years of training to make blood draws as quick and painless as possible. Let your doctor and the medical professional doing the blood draw know if you’ve ever had problems with blood tests before, if you have a bleeding disorder, or if you bruise easily, so they can take extra precautions. 

WebMD Medical Reference

Sources

SOURCES:

Asian Pacific Journal of Cancer Prevention: “Comparison of Salivary and Serum Soluble CD44 Levels between Patients with Oral SCC and Healthy Controls.”

British Society for Immunology: “Enzyme-linked immunosorbent assay (ELISA).”

‌Centers for Disease Control and Prevention: “Rocky Mounta

European Medical Journal: “Pernicious Anaemia: Mechanisms, Diagnosis, and Management.”

Food and Drug Administration: “COVID-19 ELISA pan-Ig Antibody Test.”

‌Mayo Clinic: “Lyme disease.”

‌National Health Service: “Overview: Blood tests.”

‌National Heart, Lung, and Blood Institute: “Blood Tests.”

‌Stanford Health Care: “Enzyme-Linked Immunosorbent Assay (ELISA).”

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