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Cytomegalovirus IgG and IgM antibodies

TORCH · also called CMV serology

What it measures

Measures antibodies to cytomegalovirus, the most common congenital viral infection. It is used in pregnancy, transplant donors/recipients and suspected mononucleosis-like illness.

Specimen and preparation

Specimen: Serum
Tube: Gold top

Reference range

Group	Range
IgG	Negative
IgM	Negative

Reference ranges differ between laboratories, methods and populations. Always use the range printed on your own lab report.

Causes of high values

IgG+ IgM−: past infection (latent)
IgM+: primary infection, reactivation or reinfection
IgG seroconversion: definite primary infection

Method

CLIA/ELISA; IgG avidity

Good to know

IgM is not specific for primary infection; low IgG avidity supports recent primary infection. Congenital CMV is confirmed by PCR on newborn urine or saliva within 3 weeks.

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