• Also Known As:
  • Mononucleosis Spot Test
  • Mononuclear Heterophile Test
  • Heterophile Antibody Test
  • Monospot
  • Formal Name:
  • Infectious Mononucleosis Rapid Test
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At a Glance

Why Get Tested?

To detect and help diagnose infectious mononucleosis (mono)

When To Get Tested?

When a person, especially an adolescent, has symptoms of mononucleosis, including fever, sore throat, swollen glands, and fatigue

Sample Required?

A blood sample drawn from pricking of your fingertip or from a vein in your arm

Test Preparation Needed?


You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

Infectious mononucleosis, commonly called mono, refers to an infection usually caused by the Epstein-Barr virus (EBV). The mono test detects proteins in the blood called heterophile antibodies that are produced by the immune system in response to an EBV infection.

Infectious mononucleosis is characterized by a particular set of symptoms that most often affects adolescents. People who have mono often have a fever, sore throat, swollen glands, and fatigue. Many will also have an enlarged spleen, and a few may have an enlarged liver. Symptoms of the infection usually arise about one month after the initial infection and may last for several weeks. The associated fatigue may last for several months. Mono is usually a self-limiting condition; the symptoms resolve without any specific treatment.

Epstein-Barr virus is very common and very contagious. According to the Centers for Disease Control and Prevention (CDC), most people in the United States are infected by EBV at some point in their lives. The virus is present in the saliva of an infected person and is easily spread from person to person through close contact such as kissing and through sharing utensils or cups.

Most of the time, EBV infection occurs in childhood and causes few or no symptoms. However, it can cause symptoms associated with infectious mononucleosis in about 25% of teens and young adults, according to the CDC. Mono can affect anyone at any age, but its prevalence is highest in populations of young people, such as students in high schools or colleges, or in the military.

The mono test is 71% to 90% accurate and may be used as an initial test for diagnosing infectious mononucleosis. However, the test does have a 25% false-negative rate due to the fact that some people infected with EBV do not produce the heterophile antibodies that the mono test is designed to detect. If a mono test is negative and suspicion it still high, then a test specific for EBV antibodies is usually performed.

A complete blood count (CBC) and blood smear are usually also performed, as mono is also characterized by a high white blood cell (WBC) count and the presence of atypical white blood cells (usually reported as reactive lymphocytes) as seen on a blood smear.

According to the CDC, examples of other causes of mono include:


Common Questions

How is it used?

The mononucleosis test is used to help determine whether a person with symptoms has infectious mononucleosis (mono). The test is used to detect proteins in the blood called heterophile antibodies that are produced by the immune system in response to an Epstein-Barr virus (EBV) infection, the most common cause of mono.

A mono test is frequently ordered along with a complete blood count (CBC). The CBC is used to determine whether the number of white blood cells (WBCs) is elevated and whether a significant number of reactive lymphocytes are present. Mono is characterized by the presence of atypical white blood cells.

If the mono test is initially negative but the healthcare practitioner still suspects mono, a repeat test done a week or so later may be used to determine whether heterophile antibodies have developed. If the mono test is persistently negative, a test specific for EBV antibodies may be used to help confirm or rule out the presence of an EBV infection. A strep test may also be ordered along with a mono test to determine whether a person’s sore throat is due to strep throat (group A streptococcal infection) instead of or in addition to mononucleosis.

When is it ordered?

The mono test is primarily ordered when a person, especially a teen or young adult, has symptoms that a healthcare practitioner suspects are due to infectious mononucleosis. Symptoms can sometimes be confused with those of a cold or the flu. Some of the more common signs and symptoms of mono include:

  • Fever
  • Headache
  • Sore throat
  • Swollen glands in the neck and/or armpits
  • Extreme weakness or fatigue

Some people may experience additional signs and symptoms such as:

  • Stomach pain
  • Enlarged liver and/or spleen
  • Rash

The test may be repeated when it is initially negative but suspicion of mono remains high.

What does the test result mean?

A positive mono test with an increased number of white blood cells and reactive lymphocytes on a blood smear in the presence of symptoms associated with mono indicates a likely diagnosis of infectious mononucleosis.

A negative mono test requires careful interpretation.

  • If symptoms and reactive lymphocytes are present but the mono test is negative, then it may be too early to detect the heterophile antibodies or the affected person may be one of a small percentage of people who do not make heterophile antibodies. The mono test may be repeated at a later time and/or tests specific for EBV antibodies may be performed to help confirm or rule out the mononucleosis diagnosis.
  • Most infants and young children will not make heterophile antibodies, so they will have negative mono tests even when infected with EBV. This population is rarely tested, however, because they do not usually have symptoms of infectious mononucleosis.
  • People with negative mono tests and few or no reactive lymphocytes may be infected by another microorganism that is causing symptoms, such as a cytomegalovirus (CMV) or toxoplasmosis. If the infection occurs during pregnancy, it can be important to determine the cause since some of these other infections have been associated with pregnancy complications and injury to the fetus. It is also important to identify strep throat when present because it requires prompt treatment with antibiotics. (Since EBV is a virus, it cannot be treated with antibiotics.)

Is there anything else I should know?

The mono test is rapid and easy to perform, but it is specific for heterophile antibodies, not EBV. It can also be positive in people with lymphoma, lupus, and some gastrointestinal cancers, although it is not used as a diagnostic or screening tool for these conditions.

When the mono test is negative and/or a healthcare practitioner wants to obtain more information about the presence and status of an EBV infection, the healthcare practitioner may order one or more of a combination of EBV antibodies. These tests can indicate whether a person is susceptible to EBV, has had a recent infection, has had EBV infection in the past, or has a reactivated EBV infection.

Heterophile antibodies decline after the sixth week of illness, and the mono test will become negative as the infection resolves.

How serious is a case of infectious mononucleosis?

The symptoms of the disease usually resolve with supportive treatment, such as plenty of rest and fluids, in one to four months. Sometimes, your spleen or liver may enlarge and you may have to limit your activity until these organs return to normal size. Heart problems or involvement of the central nervous system occur only rarely. Infectious mononucleosis may cause severe liver failure in males with a special XLP gene. In this rare case, mononucleosis can be fatal.

Is mononucleosis really a "kissing disease"?

The spread of Epstein-Barr virus (EBV) requires contact with the saliva of an infected person as occurs with kissing; however, kissing does not have to occur for infection to arise. Saliva on children’s toys, water bottles, toothbrushes, drinking glasses, and hands can also transmit the virus. Transmission of this virus through the air or blood does not normally occur. The incubation period, or the time from infection to appearance of symptoms, ranges from 4 to 6 weeks.

People who have infectious mononucleosis can spread the infection to others for a period of weeks. Many healthy people who have been previously infected can carry and spread the virus intermittently for life, and testing them for the virus is not practical. For these reasons, it is almost impossible to prevent spreading the virus and nearly everyone will have had an EBV infection, but not necessarily mono, by the time that they are 40 years old.

Does the Epstein-Barr virus (EBV) cause chronic fatigue syndrome?

To date, there is no laboratory evidence indicating that EBV infection causes chronic fatigue syndrome. For more information, visit the Centers for Disease Control and Prevention’s web page on Chronic Fatigue Syndrome.

Can I get infectious mononucleosis more than once?

Although the symptoms of infectious mononucleosis usually go away in 1 or 2 months, EBV remains inactive in a few cells in the body for the rest of the person’s life. Periodically, the virus can reactivate, and it is commonly found in the saliva of infected persons. This reactivation usually occurs without symptoms of illness.

Can EBV cause other serious illnesses?

EBV has been linked to certain cancers, such as Burkitt’s lymphoma, Hodgkin’s disease, nasopharyngeal carcinoma, and AIDS-related lymphoma, and continues to be studied for possible linkages to other cancers. The incidence of these diseases is low, and cases of Burkitt’s lymphoma and nasopharyngeal carcinoma occur primarily outside of the United States.

Health Professionals – LOINC

Logo for LOINC from RegenstriefLOINC Observation Identifiers Names and Codes (LOINC®) is the international standard for identifying health measurements, observations, and documents. It provides a common language to unambiguously identify things you can measure or observe that enables the exchange and aggregation of clinical results for care delivery, outcomes management, and research. Learn More.

Listed in the table below are the LOINC with links to the LOINC detail pages.

LOINC LOINC Display Name
22344-6 Heterophile Ab after absorption (S) [Titer]
5216-7 Heterophile Ab after absorption LA (S) [Titer]
7915-2 Heterophile Ab after guinea pig cell absorption (S) [Titer]
7914-5 Heterophile Ab after beef cell absorption (S) [Titer]
11610-3 Heterophile Ab Qn (S)
69420-8 Heterophile Ab IA Ql (Bld)
6425-3 Heterophile Ab IA Ql
31418-7 Heterophile Ab Ql (S)
5213-4 Heterophile Ab LA Ql (S)
12221-8 Heterophile Ab Sheep Cell Agglutination Ql (S)
43020-7 Heterophile Ab (S) [Titer]
6424-6 Heterophile Ab Aggl (S) [Titer]
5215-9 Heterophile Ab LA (S) [Titer]


View Sources

Sources Used in Current Review

(Jan 2014) Centers for Disease Control and Prevention. About Infectious Mononucleosis. Available online at http://www.cdc.gov/epstein-barr/about-mono.html. Accessed June 13, 2016.

(Mar 2011) Cohen, J. et al. Blood. Characterization and treatment of chronic active Epstein-Barr virus disease: a 28-year experience in the United States. Available online at http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3112034/. Accessed June 14, 2016.

(Oct 2015) Cunha, B. Medscape. Infectious Mononucleosis Workup. Available online at http://emedicine.medscape.com/article/222040-workup. Accessed June 13, 2016.

(Mar 2015) Womack, J. and Jimenez, M. American Association of Family Physicians. Common Questions about Infectious Mononucleosis. Available online at http://www.aafp.org/afp/2015/0315/p372.html. Accessed June 13, 2016.

Sources Used in Previous Reviews

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby’s Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO. Pp 594-595.

Corbett, JV. Laboratory Tests & Diagnostic Procedures with Nursing Diagnoses, 4th ed. Stamford, Conn.: Appleton & Lang, 1996. Pp. 373-374.

Ebell, M. (2004 October 1). Epstein-Barr Virus Infectious Mononucleosis. American Family Physician [On-line journal]. Available online at http://www.aafp.org/afp/20041001/1279.html.

Schmid, S., Leader Herpesvirus Group (2005 September 13, Updated). Epstein-Barr Virus and Infectious Mononucleosis. CDC, National Center for Infectious Diseases [On-line information]. Available online at http://www.cdc.gov/ncidod/diseases/ebv.htm.

National Center for Infectious Diseases. Epstein-Barr Virus and Infectious Mononucleosis. Available online at http://www.cdc.gov/ncidod/diseases/ebv.htm.

Nebraska Health and Human Services System. Infectious Mononucleosis (Mono) Disease Fact Sheet. Available online at http://www.hhs.state.ne.us/epi/epimono.htm.

Pagana, K. D. & Pagana, T. J. (© 2007). Mosby’s Diagnostic and Laboratory Test Reference 8th Edition: Mosby, Inc., Saint Louis, MO. Pp 662-663.

Cunha, B. (Updated 2008 October 17). Infectious Mononucleosis. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/222040-overview. Accessed May 2009.

Omori, M. (Updated 2009 April 02). Mononucleosis. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/784513-overview. Accessed May 2009.

Smith, D. S. (Updated 2008 September 3). Mononucleosis. MedlinePlus Medical Encyclopedia eMedicine [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000591.htm. Accessed May 2009.

Smith, D. S. (Updated 2008 September 3). Mononucleosis spot test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003454.htm. Accessed May 2009.

Vorvick, L. (2012 May 15). Mononucleosis spot test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003454.htm. Accessed November 2012.

Omori, M. (Updated 2012 May 23). Mononucleosis in Emergency Medicine. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/784513-overview. Accessed November 2012.

Cunha, B. and Levy, C. (Updated 2011 September 21). Infectious Mononucleosis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/222040-overview. Accessed November 2012.

Mayo Clinic Staff (2010 June 26). Mononucleosis. Mayo Clinic [On-line information]. Available online at http://www.mayoclinic.com/print/mononucleosis/DS00352/DSECTION=all&METHOD=print. Accessed November 2012.

Vorvick, L. (2012 May 15). Mononucleosis MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/000591.htm. Accessed November 2012.

Hirsch, L. (Reviewed 2011 January). Mononucleosis. Nemours Foundation [On-line information]. Available online at http://kidshealth.org/parent/infections/common/mono.html. Accessed November 2012.

Pagana, K. D. & Pagana, T. J. (© 2011). Mosby’s Diagnostic and Laboratory Test Reference 10th Edition: Mosby, Inc., Saint Louis, MO. Pp 683-684.

Kasper DL, Braunwald E, Fauci AS, Hauser SL, Longo DL, Jameson JL, eds (2005). Harrison’s Principles of Internal Medicine, 16th Edition, McGraw Hill, Pp1046-1048.

Henry’s Clinical Diagnosis and Management by Laboratory Methods. 21st ed. McPherson R, Pincus M, eds. Philadelphia, PA: Saunders Elsevier: 2007, Pp 555-556.


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