Mononucleosis (Blood)

Does this test have other names?

Mono test, monospot test, Epstein-Barr antibody test

What is this test?

This test looks for signs in your blood that you have the Epstein-Barr virus.

The Epstein-Barr virus (EBV) is a common virus that's part of the herpes virus family. It causes infectious mononucleosis, or mono. Mono is passed from person to person through saliva. Symptoms usually appear within 4 to 6 weeks after exposure and ease in 1 to 2 months.

If you have mono, you may have a high level of a type of white blood cell called a lymphocyte in your blood. Your immune system also will make certain types of antibodies (heterophile antibodies) to fight off the EBV. These antibodies will also appear in your blood if you have mono.

Why do I need this test?

You may need this blood test if your doctor suspects that you have mononucleosis. Symptoms include:

• Fatigue or exhaustion.

• Enlarged spleen.

• Swollen glands.

• Sore throat.

• Fever.

What other tests might I have along with this test?

Your doctor may also order a test for EBV-specific antibodies. It confirms the results of your blood test and gets a definitive mono diagnosis.

Your doctor may also do a throat culture to rule out strep throat as the cause of your symptoms. They may also order a complete blood count and chest X-ray.

What do my test results mean?

Test results may vary depending on your age, gender, health history, and other things. Your test results may be different depending on the lab used. They may not mean you have a problem. Ask your doctor what your test results mean for you.

Results are given in micrograms per liter (mcg/L). Normal ranges for lymphocytes are 1,000 to 4,800 mcg/L. The normal value for heterophile antibodies is zero.

If you have high levels of lymphocytes and heterophile antibodies are found, it means that you may have mononucleosis.

How is this test done?

The test is done with a blood sample. A needle is used to draw blood from a vein in your arm or hand. Sometimes the sample may be taken from a fingertip.

Does this test pose any risks?

Having a blood test with a needle carries some risks. These include bleeding, infection, bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may feel a slight sting or pain. Afterward, the site may be sore. 

What might affect my test results?

HIV, lupus, lymphoma, rubella, hepatitis, and other viral infections may cause a false-positive result.

How do I get ready for this test?

You don't need to prepare for this test. Be sure your doctor knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.