Does this test have other names?
CMV (serum), cytomegalovirus serologic test, cytomegalovirus antibody, IgG, IgM
What is this test?
This test looks for antibodies to cytomegalovirus (CMV), a virus in the herpes family,
in your blood.
CMV is so widespread that most people in the U.S. have been infected by the time they
reach age 40, although many don't realize it. You can pick up the virus by handling
or exchanging bodily fluids, such as saliva, blood, urine, breast milk, and semen.
The virus usually causes only a mild illness, but it can do serious harm to unborn
children, people with HIV/AIDS, or others with a weak immune system.
Antibodies are germ-fighting molecules that your immune system makes in response to
infection. If you have CMV-specific antibodies in your blood, you may have a CMV infection.
Like other herpes family viruses, cytomegalovirus hides in the body after the first
infection and can flare up again. Later infections tend to be milder. In fact, in
adults with a healthy immune system, the first infection may not have any symptoms.
Why do I need this test?
You may have this test if you have unexplained symptoms that resemble the flu. If
you've been infected with the virus, you may have these signs and symptoms:
You may also have this test if you are pregnant, have HIV or are a transplant donor
or recipient. If you have a current infection, your healthcare provider can give you
certain medicines to reduce the danger of congenital CMV in infants or of active illness
in people with a weakened immune system.
Only a lab test can confirm that you have CMV.
What other tests might I have along with this test?
Your healthcare provider may also order other tests for CMV antibodies. These include
tests of your cerebrospinal fluid (CSF) and urine. Your healthcare provider may also
order tests to look for CMV antigens that CMV antibodies are meant to fight. A CMV
antigen test may be called a CMV antigen assay or a CMV Ag test. (Ag stands for antigenemia,
Your healthcare provider may also order a test called polymerase chain reaction to
hunt for the DNA of CMV in your urine, saliva, blood, CSF, or biopsy tissue. He or
she may also order a viral culture test from any of these sample types.
Your healthcare provider may also order:
He or she may also test for pneumonia, hepatitis, and gastrointestinal problems.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses
to do the test. Even if your test results are different from the normal value, you
may not have a problem. To learn what the results mean for you, talk with your healthcare
Results are given in amounts of two kinds of antibodies: immunoglobulin M (IgM) and
immunoglobulin G (IgG).
If your IgM and IgG levels are high, it may mean you have CMV. Your healthcare provider
will likely give you the test again in two weeks to confirm the infection. If your
IgG levels rise between the first and second test, that may mean you have an active
infection. The fact that your IgG level increases is more important than the amount
of IgG found. The increase shows that your immune system is busy fighting an infection
and that the antibodies are not just left over from an earlier fight.
If your results are higher, it may also mean that you have a connective tissue autoimmune
disease, such as rheumatoid arthritis or systemic lupus erythematosus.
If your immune system is weakened, you may have lower results even with an active
How is this test done?
The test requires a blood sample, which is drawn through a needle from a vein in your
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection,
bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight
stinging sensation or pain. Afterward, the site may be slightly sore.
What might affect my test results?
Other factors aren't likely to affect your results.
How do I get ready for this test?
You don't need to prepare for this test. But be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illicit drugs you may use.