Rubella - IgM

Bacterial/ Viral

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Details

Measures the presence and level of Immunoglobulin G (IgM) antibodies against the Rubella virus in the blood

₹199₹660

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Rubella - IgM Test Information Guide

Why is it done?
- Detects IgM antibodies to rubella virus, indicating acute or recent rubella infection
- Used to diagnose acute rubella infection in symptomatic patients presenting with rash, fever, and lymphadenopathy
- Ordered during pregnancy to rule out rubella infection, as rubella poses significant risk of congenital rubella syndrome (CRS) with potential birth defects
- Performed in non-immune individuals with potential rubella exposure or recent vaccination concerns
- Utilized in healthcare settings to screen exposed individuals and prevent nosocomial transmission
- Typically performed when clinical symptoms of rubella appear (usually 14-23 days after exposure) or immediately after potential exposure during pregnancy
Normal Range
- Negative Result: Less than 0.9 IU/mL (or negative by qualitative assay)
- Borderline/Equivocal Result: 0.9 - 1.0 IU/mL (requires repeat testing or confirmation)
- Positive Result: Greater than 1.0 IU/mL (or positive by qualitative assay)
- Units: IU/mL (International Units per milliliter) or qualitative (negative/positive)
- Normal vs Abnormal: Negative result indicates no acute rubella infection or recent rubella immunity. Positive result indicates acute or recent rubella infection, requiring clinical correlation and possible follow-up testing
Interpretation
- Negative Result: No acute rubella infection detected. Patient either has no current infection or is beyond the IgM detection window (typically appears 1-2 weeks after symptom onset and wanes over 4-8 weeks). May indicate immunity from prior vaccination or infection if accompanied by positive IgG
- Positive Result: Indicates acute or recent rubella infection (typically within 4-8 weeks of symptom onset). In pregnant patients, confirms rubella infection with risk of congenital rubella syndrome. Requires immediate clinical management and contact tracing if infectious period
- Equivocal Result: Borderline values require repeat testing within 2-4 weeks. May indicate early infection with rising titers, waning infection approaching negative threshold, or rare cross-reactivity. Confirmation with IgG testing or paired sera comparison recommended
- Factors Affecting Results: Timing of specimen collection relative to symptom onset; immunocompromised status may result in false negative or delayed antibody response; recent rubella vaccination may cause positive result; presence of rheumatoid factor or other autoimmune antibodies may interfere with results
- Clinical Significance: IgM antibodies are most specific for acute infection; combination with IgG testing provides comprehensive assessment; serial titers or paired sera with fourfold rise in IgG supports acute infection diagnosis; particularly critical in pregnancy for determining congenital transmission risk
Associated Organs
- Primary System: Immune system with viremia spreading to multiple organ systems including lymphoid tissue, skin, joints, and nervous system
- Associated Medical Conditions: Acute rubella infection, congenital rubella syndrome, rubella arthralgia/arthritis, rubella encephalitis, thrombocytopenia, myocarditis
- Diseases Diagnosed: German measles (rubella), congenital rubella syndrome (CRS), rubella-associated arthritis, rubella encephalitis, post-infectious complications
- Potential Complications: In children: encephalitis, thrombocytopenia, myocarditis. In pregnant women: spontaneous abortion, stillbirth, premature delivery, congenital defects including cardiac abnormalities, cataracts, deafness, intellectual disability, growth restriction, microcephaly, and other manifestations of congenital rubella syndrome
Follow-up Tests
- Rubella IgG Antibodies: Confirms immunity status and chronic/past infection; helps differentiate acute infection from prior immunity
- Serial Rubella IgM Titers: If initial result equivocal, repeat testing 2-4 weeks later; rising titers confirm acute infection while falling titers suggest waning antibody response
- Paired Sera Comparison: Acute phase serum and convalescent phase serum (2-3 weeks later) with fourfold rise in IgG titers confirming acute infection diagnosis
- Rubella PCR/Viral Culture: Detects viral RNA or isolates virus from respiratory secretions, throat swabs, or urine; particularly useful for diagnosis in immunocompromised patients
- Infectious Disease Consultation: Recommended for pregnant patients with positive results or suspected congenital rubella syndrome
- Fetal Testing (if pregnant): Amniocentesis with rubella PCR after 18 weeks gestation; cordocentesis for earlier diagnosis if high risk
- Monitoring Frequency: Single test usually sufficient for diagnosis; repeat only if equivocal (2-4 weeks later) or for clinical reassessment in pregnant patients
Fasting Required?
- Fasting Required: No
- Specimen Collection: Blood sample via venipuncture; serum separator tube (SST) is standard
- Patient Preparation: No special preparation required; can eat and drink normally before test; maintain normal activities; wear loose-fitting clothing for easy arm access
- Medications: No medications need to be avoided; continue all regular medications including immunosuppressants and antivirals as prescribed
- Timing Considerations: Ideally collect specimen 1-2 weeks after symptom onset for optimal IgM detection; if initial test negative but clinical suspicion remains, repeat 2-4 weeks later
- Special Instructions: Inform healthcare provider of recent rubella vaccination (within 2-4 weeks), immunosuppressive conditions, or medications; note exact date of symptom onset for clinical correlation

How our test process works!