Exams and Tests

The doctor will rely on a combination of clinical and laboratory findings to diagnose mononucleosis. The doctor will ask about the course of the illness and perform a physical exam.

The following blood tests can help confirm the diagnosis:

• A complete blood count may show the white blood cell count to be high because of the infection.
  
  
• Liver function tests show elevation of liver enzyme levels in nearly 90% of people with mono.
  
  
• A test that measures a type of antibody known as heterophile antibody is often performed. Heterophile antibodies are present in about 80%-90% of people with mono. They form in response to infection with Epstein-Barr virus as well as in other infections.
  
  
  • This test result is frequently negative in young children or early in the course of the disease.
    
    
  • The qualitative heterophile antibody test (Monospot) gives either a positive or negative result. This test takes minutes to perform and provides results right away.
    
    
  • Epstein-Barr virus specific antibody testing may be used for people with suspected mononucleosis who have heterophile antibody test results that are negative. It can also be used to test for atypical cases of mononucleosis or in young children who are suspected of having mononucleosis.