Rubella Antibody, IgM
|Plasma Separator Tube 4.5 mL
Call laboratory for additional acceptable specimen collection containers.
3.0 mL whole blood from light green top tube or TWO Microtainer® devices.
24 hrs/day, 7 days a week, including holidays.
3 hours (upon receipt in laboratory)
Reference range and methodology changed effective 12/11/2012.
0.8 AI or less: Negative - No significant level of detectable rubella
0.9-1.0 AI: Equivocal - Repeat testing in 10-14 days may be
1.1 AI or greater: Positive - IgM antibody to rubella detected, which
may indicate a current or past rubella infection .
For workup related to possible rubella infection, acute and
convalescent specimens must be labeled as such; parallel testing is
preferred and convalescent specimens must be received within 30 days
from receipt of the acute specimens. Please mark specimen plainly
as "ACUTE" or "CONVALESCENT."
In children and adults, rubella infection usually results in a mild
exanthematous disease. However, infection during pregnancy,
particularly in the first trimester, can result in fetal death or
the "rubella syndrome," a spectrum of congenital defects that includes
cataracts, deafness, glaucoma, congenital heart disease, and mental
retardation. About ten to 20 percent of newborns infected in utero fail
to survive past the first year of life. Since complications of
congenital rubella infection are so severe, diagnosis of infection
during the first trimester of pregnancy may influence the decision to
terminate or continue the pregnancy.
IgM antibodies become detectable in a few days after the onset of signs
and symptoms and reach peak levels in seven to ten days. These
antibodies persist, but rapidly diminish in concentration over the next
four to five weeks until the antibody is no longer clinically
detectable. The presence of IgM antibody in a single specimen suggests
that the patient has recently experienced a rubella infection. In most
cases, the infection probably occurred within the preceding one to
three months. Rubella IgM antibody in a newborn's serum suggests
congenital infection since IgM from the mother is not transferred to
the infant across the placenta. The infected infant, in contrast to a
woman with prenatal rubella, may continue to produce rubella-specific
IgM for several months.
Multiplex Flow Immunoassay