Histoplasma Antigen Immunoassay

CERNER / EPIC MNEMONIC: HISTO AG
CPT CODE: 87385; 87999
CDM NUMBER: 3511033; 3511023
DAYS PERFORMED: Test performed Monday-Friday only.
TURNAROUND TIME: 2-7 days
CONTAINER TYPE: Sealed sterile urine container (no preservative); red top Vacutainer tube or SST tube; sealed sterile cerebrospinal fluid collection tube; sealed sterile sputum or Leuken`s container
SPECIMEN REQUIREMENTS: Urine, blood (serum), CSF, bronchial
REJECTION CRITERIA: Excessive hemolysis, gross contamination of specimen, chylous serum, improper storage of specimen, inappropriate specimen container, insufficient specimen volume.
MINIMUM VOLUME: 3 mL urine, 5 mL blood (2 mL serum), 1 mL CSF, 5 mL bronchial
HANDLING INSTRUCTIONS: Specimen should be transported as soon as possible. When transportation is delayed, refrigerate.
REFERENCE RANGE: Negative (i.e. <1.0)EIA Units Initial testing interpretations:- equivocal: result inconclusive after repeated testing- <1.0: negative- 1.0-2.0: weak positive, suggest repeat testing-/>2.0: positive, repeat if inconsistent with clinical findings. Follow-up testing interpretations:- no change, decrease, increase- <2.0: stable- 2.1-4.0: mild increase, possible failure, suggest repeat -/>4.0: moderate to marked increase, probable failure
METHODOLOGY: Enzyme immunoassay (EIA)
REFERRAL LABORATORY: Commercial Laboratory
ADDITIONAL INFORMATION: The sensitivity of antigen detection is greater using urine rather than serum specimens (i.e. 92% versus 82% respectively) in disseminated disease. Antigen is detected less frequently in patients with self limited diseases (39%) and chronic pulmonary histoplasmosis (21%). In cases of acute pulmonary infection, the sensitivity is greater than 75% for more severe cases presenting with diffuse pulmonary infiltrates and respiratory insufficiency. Antigen may be detected in the cerebrospinal fluid of 40-67% of patients with Histoplasma meningitis and in bronchoalveolar lavage fluid of 70% of patients with AIDS who have extensive pulmonary histoplasmosis.Specificity is at least 98% with significant cross reactivity with Paracoccidioides brasiliensis, Blastomyces dermatiditis, and Penicillium marneffei.