What is the CMV IgG Test?
Cytomegalovirus immunoglobulin G is produced by the body in response to cytomegalovirus infection that occurred in the past or an active infection. CMV belongs to the herpes family and usually remains dormant in the body after the first infection. The cytomegalovirus is less harmful to many people but can pose serious health complications to pregnant women, newborns or individuals with compromised immunity due to chemotherapy, organ transplant or is affected with HIV/AIDS.
CMV IgG test is conducted to assess the immunity and the potential health complications caused by exposure to the cytomegalovirus. The CMV IgG antibodies provide long-term protection against the CMV and are suggestive of past exposure.
How is the Test Performed?
CMV IgG test is a straightforward test requiring a blood sample;
Preparation
- Fasting is generally not required for the test.
- Inform your doctor about the medications you are taking for accurate interpretation of the result.
Collection
- A trained phlebotomist cleans the area with an alcoholic pad and draws the blood using a needle.
- The sample is sent to the laboratory for further analysis.
Laboratory Analysis
- The sample is analyzed in the laboratory using techniques such as enzyme-linked immunosorbent assay (ELISA) and chemiluminescence immunoassay (CLIA).
What are the symptoms that prompt this test?
This test is recommended for individuals exhibiting the symptoms of exposure to the cytomegalovirus or if an individual belongs to the high-risk group;
Symptoms in Pregnant Women
- Fever
- Swollen lymph nodes or glands
- Tiredness or fatigue without a known reason
Symptoms in Newborns
- Low birth weight
- Small head
- Jaundice
- Abnormalities in hearing and vision
- Enlargement of liver or spleen
General Symptoms
- Unexplained fever
- Swollen lymph nodes
- Fatigue
What are Normal Ranges for This Test?
The generally accepted ranges for the presence or absence of the virus are mentioned below;
Negative – Less than 0.8 IU/mL (susceptible to primary infection)
Equivocal – 8 to 1.0 IU/mL (inconclusive result)
Positive – More than 1.0 (past exposure)
**The above-mentioned values are for general guidelines only and vary according to the assay of the test used by the laboratory. **
What Happens if Test Results Show Abnormal Levels?
If abnormal levels of CMV IgG are detected in an individual the doctor may warrant further testing such as CMV DNA PCR for the assessment of the viral load, medications, and management of the infection. The following steps are taken to manage the infection;
- If CMV infection is present in a pregnant woman, the doctor recommends additional diagnostic tests including amniocentesis for the assessment of the risk to the fetus.
- Doctors often recommend antiviral therapy such as ganciclovir and valganciclovir for individuals with compromised immunity.
- Regular monitoring and antiviral treatment is given to the newborns in case of congenital infection.
