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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 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 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 healthcare provider suspects that you have mononucleosis. Signs and symptoms include:

  • Fatigue or exhaustion

  • Enlarged spleen

  • Swollen glands

  • Sore throat

  • Fever

What other tests might I have along with this test?

Your healthcare provider may also order a test for EBV-specific antibodies to confirm the results of your blood test and get a definitive mono diagnosis.

Your healthcare provider may also order a complete blood count (CBC) and chest X-ray.

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider 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. 

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 healthcare provider knows about all medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illicit drugs you may use.

Medical Reviewers:

  • Fraser, Marianne, MSN, RN
  • Haldeman-Englert, Chad, MD