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Mononucleosis (Blood)

Does this test have other names?

Mono test, monospot test, Epstein-Barr 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 herpesvirus family. It causes infectious mononucleosis, or mono. Mono is passed from person to person through saliva. Symptoms usually appear within four to six weeks after exposure and ease in one to two 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 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 have 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 to confirm the results of your blood test and get a definitive mono diagnosis.

What do my test results mean?

Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your health care provider.

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 requires a blood sample, which is drawn through a needle from a vein in your arm.

Does this test pose any risks?

Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly 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.