What is the interpretation of a positive CMV (Cytomegalovirus) IgG, elevated CMV IgM, negative CMV PCR, and pending CMV avidity test results?

From the Guidelines

The patient is likely to have a past or chronic CMV infection rather than an acute one, as indicated by the positive CMV IgG result, which suggests previous exposure to CMV 1.

Key Findings

• The elevated CMV IgM result may indicate a reactivation or persistent infection, but it can also be a false positive due to other causes such as EBV infection or an activated immune system 1.
• The negative CMV PCR result suggests that the virus is not currently actively replicating at detectable levels.
• The pending CMV avidity test result is crucial in differentiating between recent and past infections.

Clinical Implications

• Until the CMV avidity result is available, it is recommended to exercise caution and consider the patient as potentially infectious, especially in immunocompromised individuals or pregnant women.
• Precautions should be taken to prevent potential transmission, such as using personal protective equipment and practicing good hygiene.
• If the patient is pregnant or immunocompromised, consider consulting with a specialist for further guidance on management and potential antiviral therapy, such as valganciclovir, if necessary 1.

Next Steps

• Await the CMV avidity test result to confirm the diagnosis and guide further management.
• Consider consulting with a specialist for further guidance on management and potential antiviral therapy, if necessary.
• Continue to take precautions to prevent potential transmission until the CMV avidity result is available.

From the Research

Interpretation of CMV Test Results

The interpretation of a positive CMV (Cytomegalovirus) IgG, elevated CMV IgM, negative CMV PCR, and pending CMV avidity test results can be complex and depends on various factors, including the individual's immune status and medical history.

• A positive CMV IgG result indicates that the individual has been infected with CMV at some point in their life and has developed immunity to the virus 2, 3.
• Elevated CMV IgM levels suggest a recent or current CMV infection, as IgM antibodies are typically produced in response to an acute infection 2, 3.
• A negative CMV PCR result indicates that the virus is not currently active in the body, as PCR tests detect the presence of viral DNA 4, 5.
• The pending CMV avidity test result will help determine whether the infection is recent or past, as low avidity indices are typically seen in recent infections, while high avidity indices indicate past infections 3, 6.

Clinical Implications

The combination of these test results may indicate a recent CMV infection in an individual with a history of previous exposure to the virus.

• In immunocompetent individuals, CMV infection can range from asymptomatic to mononucleosis, while in immunocompromised individuals, it can lead to more severe complications, such as pancreatitis or respiratory failure 2, 4, 5.
• The risk of CMV recurrence is dependent on the level of immune suppression, and certain groups, such as hematopoietic stem cell transplantation recipients, are at higher risk of CMV recurrence and disease 5.
• Chronic CMV infection, as defined by detectable CMV DNA in peripheral monocytes, may contribute to T-cell immunosenescence, chronic inflammation, and adverse health outcomes in older adults 3, 6.