Understanding Lab Tests for Mononucleosis
Written by Private MD Labs Medical Writing Team • Last Updated: September 8, 2025
Mononucleosis, commonly called mono or the "kissing disease," is a viral infection that causes symptoms like fever, sore throat, swollen lymph nodes, and extreme fatigue. While the symptoms are often distinctive, specific blood tests are essential to confirm the diagnosis and identify which virus is causing the infection.
Top Recommended Test
IgM
High levels of IgM in the blood can indicate a recent infection with the Epstein-Barr virus, which is the primary cause of mononucleosis. IgM antibodies are typically the first to appear during an acute infection, making this test valuable for detecting active mono.
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Why Blood Tests Are Essential for Mononucleosis
Several different viruses can cause mononucleosis, including Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Since the symptoms can mimic other conditions like strep throat or other viral infections, blood tests are fundamental for accurate diagnosis and appropriate treatment planning.
Other Relevant Tests
Cytomegalovirus (CMV) Antibodies, IgG
CMV is one of the viruses that can cause mononucleosis. The presence of CMV IgG antibodies can indicate a current or past infection with the virus, which might have caused mononucleosis. This test helps determine if CMV is the underlying cause of your mono symptoms.
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Understanding Your Results
These blood tests work together to provide a comprehensive picture of viral activity in your system. Elevated IgM levels suggest a recent or active infection, while CMV antibody testing helps identify the specific virus responsible for your symptoms. Your healthcare provider will interpret these results alongside your symptoms to confirm a mononucleosis diagnosis.
Important Considerations
The information here is for educational purposes only and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.
