Test Quick Guide

Infectious mononucleosis, or mono, is a disease most frequently caused by infection with the Epstein-Barr virus (EBV). The viruses that cause mono are commonly spread through bodily fluids, especially saliva. While less common, transmission may also occur through blood and semen during sexual contact, blood transfusions, and organ transplantations.

Several tests may be used to confirm a diagnosis of infectious mononucleosis, including mononucleosis testing, also called heterophile antibody testing. Mononucleosis testing is performed with a blood sample and looks for specific substances that form in the body during the infection. Mono test results are generally available within an hour.

About the Test

Purpose of the test

The purpose of mono testing is to look for ​​heterophile antibodies in the blood, which can confirm a diagnosis of infectious mononucleosis.

Infectious mononucleosis is a contagious disease caused by a virus. EBV is the most common cause of infectious mononucleosis, although other viruses can also cause this disease. Also known as human herpesvirus 4, EBV is a member of the herpes virus family. Mono is most common among teenagers and young adults. Approximately 25% of people infected with EBV develop infectious mononucleosis.

Mono may be diagnosed based on a person’s symptoms, so laboratory tests are not always used to diagnose this condition. However, many experts recommend using laboratory tests to confirm a diagnosis of mono. Laboratory tests used in diagnosing infectious mononucleosis include mononucleosis testing, Epstein-Barr virus (EBV) antibody tests, and a complete blood count.

What does the test measure?

To determine whether a patient has infectious mononucleosis, a mono test is administered to look for the presence of certain antibodies. Antibodies are substances made by the immune system in response to an infection.

In patients who are suspected of having mono, a blood sample is tested for two antibodies that are produced during or after an EBV infection, called heterophile antibodies. Heterophile antibodies are present in 40 to 60% of patients with mono in the first week after infection and in 80 to 90% of patients by the third or fourth week after infection. These antibodies usually remain detectable for three months, although they may be present for as long as a year after infection.

When should I get a mono test?

A mono test may be ordered when a person has symptoms that a health care professional suspects are due to infectious mononucleosis. Some of the more common signs and symptoms of this disease include:

  • Extreme fatigue
  • Fever
  • Sore throat
  • Swollen lymph nodes in the neck and armpits
  • Head and body aches
  • Enlarged liver, spleen, or both
  • Rash

Finding a Mono Test

How to get tested

Collecting a blood sample used for mono testing is performed in a doctor’s office, hospital, laboratory, or other medical setting after being ordered by a healthcare professional.

Can I take the test at home?

A number of at-home test kits are available for suspected infectious mononucleosis. Available for purchase online, kits provide the materials necessary to collect a sample of blood using a finger prick. Test kits generally fall into two categories:

Self-testing kits allow users to collect a drop of blood and place it onto a test strip. An indicator window on the testing device will then provide the results of the test, usually within 3-5 minutes.

Self-collection kits involve gathering a blood sample and mailing it to the testing company for laboratory analysis. Test results are then reported via a secure online platform, generally within a few days.

How much does the test cost?

The cost of mono testing depends on a variety of factors, such as a patient’s health insurance coverage, where the test is performed, and any additional testing that is conducted at the same time. Total costs may include those associated with obtaining and analyzing the test sample as well as charges for an office visit.

Mono testing may be covered by health insurance. It may be helpful to contact the health insurance provider or the hospital or laboratory conducting the test for more information about out-of-pocket costs, such as copays or deductibles.

For patients without health insurance, or for whom insurance doesn’t cover the cost of testing, a doctor or hospital administration can further discuss the out-of-pocket cost of mono testing.

Taking a Mono Test

To conduct a mono test, your health care provider will obtain a blood sample by using either a finger prick or a small needle inserted into a vein in your arm. A small amount of blood is then placed onto a slide, test strip, or other testing device.

Before the test

Regardless of the method used to obtain a blood sample, you generally don’t need to take any special preparations for a mono test. You can check with your doctor for any pretest instructions to follow.

During the test

During the test, a health professional will either draw blood by finger prick or through a vein located on the inside of the elbow or the back of the hand.

Collecting blood through a finger prick involves several steps. First, the area is cleansed with alcohol or another type of disinfectant. Then, the skin of either the middle or ring finger is pricked with a sharp needle contained in a medical device called a lancet.

The first drop of blood is wiped away and the finger may be lightly squeezed to bring blood to the surface. The blood may be collected in a small glass tube called a pipette or placed on a slide, test strip, or other testing device.

Obtaining blood through a blood draw often begins with an elastic band being tied around the upper arm. This will make the veins beneath the band swell with blood. The site where the needle will be inserted is then cleaned with an antiseptic wipe.

Once the site is cleaned, a small needle is inserted into the vein and blood is collected into a vial or tube. Once sufficient blood is collected, the needle is removed and the elastic band is untied.
These tests usually take 5 to 10 minutes. During the test you may feel moderate pain when the needle or lancet is inserted. Some patients only feel a pinch, prick, or stinging sensation. Additionally, some people may feel faint or lightheaded. There may be some throbbing at the site after the test is finished.

After the test

After a finger prick or blood draw, pressure may be applied to the site to stop any bleeding. In some cases, a bandage may be applied to the puncture site.

There is very little risk to having either type of blood collection. You may have swelling, tenderness, inflammation, bruising, or persistent bleeding at the injection site. However, most symptoms go away quickly. Rare adverse effects include infection. Contact your doctor if you have signs of an infection or any other long-lasting effects.

Talk with your doctor if you have any concerns regarding the potential side effects associated with testing, including whether there are any restrictions to work or other activities after the test is completed

Mono Test Results

Receiving test results

While result times vary based on the type of test used, results of mono tests are generally available within 5 to 10 minutes, although some tests may take upwards of an hour. Your doctor may ask you to wait in the examination room for the results, or they may contact you at a later time to discuss test results.

Interpreting test results

In patients with symptoms consistent with infectious mononucleosis, the results of a mono test indicate whether heterophile antibodies are present. The results of a mono test are either positive or negative.

A positive test indicates the presence of heterophile antibodies. This result, alongside a patient’s symptoms, are used to make a diagnosis of infectious mononucleosis.

A negative test may indicate that a patient does not have infectious mononucleosis. However, mono testing is not always accurate and in certain situations patients may need additional testing to rule out mono as the cause of their symptoms.

Are test results accurate?

While the mono test generally performs well in detecting the presence of heterophile antibodies, it can produce relatively high rates of false-negative testing under specific circumstances. A false-negative result means that a test result is negative despite the patient having infectious mononucleosis.

Patients may sometimes receive a false-negative if the test was done too soon, generally within one to two weeks after the illness started. Mono tests can also give false-negative results in infants and children less than four years of age.

Though rare, there is evidence that the mono test may incorrectly indicate the presence of infectious mononucleosis in patients with other diseases, including:

  • Leukemia
  • Lymphoma
  • Pancreatic cancer
  • Lupus
  • HIV infection
  • Rubella, a type of measles
  • Herpes simplex virus

In patients with these conditions, Epstein-Barr virus antibody tests are generally favored for diagnosing infectious mononucleosis.

Do I need follow-up tests?

In patients with symptoms consistent with infectious mononucleosis and a positive mono test, additional testing is not generally necessary.

If a mono test is negative and a false-negative test result is possible due to testing too soon after infection, your health care provider may repeat the mono test at a later time. Additional tests, such as an Epstein-Barr virus antibody test, may also be considered.

Questions for your doctor about test results

Patients may find it helpful to ask questions about their mono test results. Questions for a patient’s doctor may include:

  • What is my test result?
  • What is my risk of false-negative results?
  • Will I need additional testing to determine whether I have infectious mononucleosis?
  • Could a positive test result be related to another disease or condition?


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