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Galactomannan, Aspergillus Antigen test by EIA -Serum
Genetic
Report in 144Hrs
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No Fasting Required
Details
Detects Aspergillus antigen.
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Galactomannan Aspergillus Antigen test by EIA - Serum
- Why is it done?
- Detects galactomannan antigen, a cell wall component of Aspergillus fungi, in serum samples using enzyme immunoassay (EIA) technique
- Screens for invasive aspergillosis, a serious fungal infection in immunocompromised patients
- Aids in early diagnosis before clinical symptoms develop
- Used in patients with hematologic malignancies, organ transplant recipients, and those receiving prolonged neutropenic therapy
- Monitors treatment response and detects recurrent infections in at-risk populations
- Typically performed during periods of immunosuppression or when fever of unknown origin suggests fungal infection
- Normal Range
- Negative Result: < 0.5 ng/mL (nanograms per milliliter) - Indicates no detectable galactomannan antigen
- Borderline Result: 0.5-1.0 ng/mL - May indicate early infection or cross-reactivity with other fungi; repeat testing recommended
- Positive Result: > 1.0 ng/mL - Consistent with invasive aspergillosis; higher values suggest active infection
- Units of Measurement: ng/mL (nanograms per milliliter) or optical density (OD) values depending on laboratory methodology
- Clinical Interpretation: Negative results reduce suspicion for invasive aspergillosis but do not exclude it; positive results warrant clinical correlation and additional diagnostic confirmation
- Interpretation
- Negative Result (< 0.5 ng/mL): Indicates absence of detectable galactomannan antigen; does not completely rule out invasive aspergillosis as sensitivity varies (approximately 70-80% in neutropenic patients)
- Borderline Result (0.5-1.0 ng/mL): Requires careful clinical correlation; may represent early infection, recovering patient, or non-Aspergillus fungi; serial testing recommended to assess trend
- Positive Result (> 1.0 ng/mL): Strongly suggests invasive aspergillosis, particularly in high-risk immunocompromised patients; specificity approximately 85-95%
- Factors Affecting Results: Timing of specimen collection (antigen appears within days to weeks of infection), degree of immunosuppression, concurrent antifungal prophylaxis (may suppress antigen levels), and sample handling procedures
- Cross-Reactivity: Can occur with other fungal species including Pentamecetia boydii, Histoplasma capsulatum, and occasionally Candida species; clinical context essential
- Serial Testing: Increasing galactomannan levels suggest progressive infection; declining levels may indicate treatment response; consecutive positive tests increase diagnostic confidence
- Associated Organs
- Primary Organs Involved: Lungs (most common site), sinuses, and blood vessels; disseminated disease can affect heart, kidneys, central nervous system, and skin
- Immune System Involvement: Immunocompromised states including prolonged neutropenia, HIV/AIDS with CD4 < 50 cells/mL, hematologic malignancies, bone marrow/stem cell transplant recipients, and solid organ transplant recipients
- Associated Diseases: Invasive pulmonary aspergillosis, chronic granulomatous disease, aspergillus sinusitis, aspergillus endocarditis, aspergillus meningitis, and disseminated invasive aspergillosis
- Potential Complications: Pulmonary hemorrhage, respiratory failure, vascular invasion leading to thrombosis and tissue infarction, and mortality rates of 40-90% depending on immune status if untreated
- Other Organ Manifestations: Hepatic abscesses, renal infarction, cardiac vegetations on valves, skin lesions from hematogenous spread, and central nervous system involvement with mass lesions
- Follow-up Tests
- High-Resolution CT Chest: Evaluates for characteristic nodules, ground-glass opacities, halo sign, and air-crescent sign suggesting invasive pulmonary aspergillosis
- Bronchoalveolar Lavage (BAL) with Fungal Culture: Gold standard for diagnosis; obtains direct specimen for fungal culture and histopathology
- Aspergillus-Specific IgG Antibodies: Helpful for chronic aspergillus infections; negative in acute invasive disease
- Galactomannan Repeat Testing: Serial specimens collected every 2-3 days during high-risk periods; helps establish trends and monitor treatment response
- Blood Cultures: Rule out other bacterial or fungal bacteremia; Aspergillus rarely isolated from blood cultures
- Beta-D-Glucan Serum Test: Complimentary marker for invasive fungal infections; higher sensitivity but lower specificity than galactomannan
- Sputum or Respiratory Specimen Culture: Not sensitive for invasive disease but may reveal colonization; useful in pulmonary symptoms
- Biopsies (Lung, Sinus, or Other): Histopathology shows tissue invasion with septate hyphae; reserved for diagnostic confirmation in selected cases
- Imaging Studies: MRI brain for CNS disease, echocardiography for endocarditis, sinus CT for rhinosinusitis
- Fasting Required?
- Fasting Required: No
- Patient Preparation: No special preparation required; routine serum blood draw by venipuncture
- Specimen Collection: 5-10 mL of serum collected in sterile tube without additives; room temperature acceptable but refrigeration preferred to maintain specimen integrity
- Medications: Continue all medications as prescribed; antifungal medications (voriconazole, liposomal amphotericin B, posaconazole, echinocandins) do not interfere with test but may affect antigen levels
- Timing Considerations: Specimen should be collected during acute illness or high-risk periods; antigen becomes detectable within 3-5 days of infection onset but may be undetectable after treatment initiation or in recovering patients
- Special Instructions: Avoid gross hemolysis; inform laboratory of immunosuppressive status for appropriate interpretation; communicate if patient on prophylactic antifungal therapy
How our test process works!
