Procedure, Kits, Accuracy & Results of Mononucleosis Test

Submitted on March 27, 2012

Mononucleosis, also known as infectious mononucleosis or just ‘mono’ is a viral infection that is spread through saliva, which is probably why it is also known as the “kissing disease”. The symptoms of mononucleosis include fever, sore throat and swollen glands and it is often mistaken for a streptococcal infection.

Apart from coming into direct contact with infected saliva, mononucleosis can also be spread by sharing crockery, cutlery and glasses as well as through transmissions with infected blood products. Mononucleosis is cause by the Epstein-Barr virus (EBV). Mononucleosis tests are blood tests that confirm the presence of the antibodies manufactured by the body’s immune system to fight the infection caused by the Epstein-Barr virus. The tests for mononucleosis include the monospot test and the EPV antibody test.

The monospot test (heterophil test) is a quick screening test for mononucleosis that helps to detect the presence of heterophil antibodies in the blood. These are antibodies that are made by the immune system in response to certain types of infections. A blood sample is taken, placed on a microscope slide and mixed with certain reagents. If the heterophil antibodies are present the blood will tend to clump or agglutinate. A positive result usually indicates mononucleosis. The test can detect the presence of antibodies from 2 to 9 weeks after a person has been infected which is why a doctor may not order this test if the infection is suspected to be in the first 7-10 days period.

In the EPV antibody test, a specific reagent that reacts to the EPV antibodies is mixed with the blood sample. The test can be used to confirm whether you have been infected recently or in the past. This test is usually performed when the doctor suspects mononucleosis infection but the monospot test has returned a negative result. EPV antibody tests may also be used to check for the presence of EBV antibodies when a person has some other disease or uses medications that affect the immune system.

Test Procedures

There are many different brands of test kits available for both types of tests, all with a fairly high degree of accuracy. You can discuss the types of test ordered with your doctor as well as any other concerns you may have. The test themselves are very straightforward.

The Monospot Test

In the monospot test, a small sample of blood is taken from the tip of your finger. First, the healthcare professional performing the procedure will swab your finger with an alcohol swab to sterilize the skin. Your finger will be massaged without touching the puncture site. A fine needle or lancet will be used to prick your fingertip and the first drop of blood will be wiped away. A small capillary tube will be used to collect the next drop of blood that forms after which a cotton swab will be pressed onto your fingertip to staunch the bleeding. The blood sample from the capillary tube will then be tested.

The EBV Antibody Test

In The EBV antibody test, blood will be drawn from your vein. The healthcare professional will tie a tourniquet around your upper arm to stop the flow of blood. You may be asked to flex your arm a few times. This will help the veins in your arms stand out clearly making it easy for the professional to puncture the vein. The spot over the vein will be sterilized with an alcohol swab. A needle attached to a syringe will be inserted into your vein and a blood sample will be aspirated. The tourniquet will then be loosened and the needle withdrawn. At the same time an alcohol swab will be pressed onto the puncture site to staunch the bleeding and a small bandage affixed to the puncture site. The collected blood sample will then be tested.

The results of the monospot test are usually ready within an hour. There are some test kits available that can give you a result within 5 to 10 minutes. If no blood clumps are detected it indicates the absence of heterophil antibodies. However, this does not mean that mononucleosis infection is not present. If the blood is not tested during the correct window (2 to 9 weeks after infection) it may give a negative result.

A positive monospot test result occurs when blood clumps form, indicating the presence of heterophil antibodies. This means that you probably have got mononucleosis but it is still not definite. A positive result may also be caused by diseases such as leukemia, lymphoma, hepatitis, rubella, lupus and rheumatoid arthritis.

For this reason the monospot test is considered to be a screening test and not a definitive test for mononucleosis. If you have symptoms of mononucleosis but test negative with the monospot test, your doctor may order the EBV antibody test to confirm the diagnosis. The monospot test is also not a viable option for children under the age of 4 years.

The problem with these tests is that many people have been exposed to EBV during childhood and carry a type of antibody known as IgG. The presence of this antibody does not mean that your EBV infection is recent.