Histoplasma and Blastomyces Antigen, Serum (Sendout)

Useful For:

• Diagnosing Histoplasma capsulatum or Blastomyces dermatitidis infection without differentiation between the organisms
• Monitoring antigen levels following initiation of antifungal treatment

Test Highlights:

• This test detects Histoplasma and Blastomyces antigen in serum, without differentiation between the 2 fungal pathogens.
• It aids in the diagnosis of histoplasmosis or blastomycosis alongside other routine methods, including culture, molecular testing, and serology.
• This test can be used to monitor response to antifungal therapy.

Reference Values:

Interpretation:

Not detected: No antigen from Histoplasma or Blastomyces detected. False-negative results may occur depending on extent of disease or site of infection. Repeat testing on a new specimen if clinically indicated.

Detected, <1.5 ng/mL: Antigen from Histoplasma or Blastomyces (unable to differentiate) was detected, below the limit of quantification (<1.5 ng/mL). Result should be correlated with clinical presentation, exposure history, and other diagnostic procedures, such as culture, serology, histopathology, and radiographic findings to aid in the differentiation between histoplasmosis or blastomycosis.

Detected, 1.5-25.0 ng/mL: Antigen from Histoplasma or Blastomyces (unable to differentiate) detected. Result should be correlated with clinical presentation, exposure history, and other diagnostic procedures, such as culture, serology, histopathology, and radiographic findings, to aid in the differentiation between histoplasmosis and blastomycosis.

Detected, >25.0 ng/mL: Antigen from Histoplasma or Blastomyces (unable to differentiate) detected, above the limit of quantification (>25.0 ng/mL). Result should be correlated with clinical presentation, exposure history, and other diagnostic procedures, such as culture, serology, histopathology, and radiographic findings, to aid in the differentiation between histoplasmosis or blastomycosis.

Cautions:

Due to significant cross-reactivity between galactomannan antigens from Blastomyces and Histoplasma, this assay does not differentiate between these 2 dimorphic fungal agents. To differentiate, consider fungal culture, molecular testing, or serology testing.

Positive results should be correlated with other clinical and laboratory findings (e.g., culture, serology).

Low-level positive antigen levels may persist following resolution of infection and completion of appropriate treatment regimen.

Sensitivity of this assay to detect antigen from species other than Blastomyces dermatitidis or Histoplasma capsulatum is unknown.

False positive results may occur less frequently with other dimorphic agents (e.g., Coccidioides).

Outside Laboratories: Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum while awaiting shipment. Transport with a cold pack.

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, gross lipemia, gross icterus, or heat-inactivated specimen.

Centrifuge sample and transfer serum to a separate plastic vial. Refrigerate serum.

Sendouts:

• Order Mayo Test: HIBAG
• Interfaced: Yes [Interface: 601; Worksheet: MARF]

Stability: Refrigerated (preferred): 28 days; Frozen: 28 days; Ambient: 72 hours.

Reject Due To: Gross hemolysis, gross lipemia, gross icterus, or heat-inactivated specimen.