Test Information

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ALPHA Histoplasma Antigen EIA

Test Code: 3700

Cpt Code:

87385 (x1)

Clinical Utility

The ALPHA Histoplasma Antigen Immunoassay is used, in conjunction with other diagnostic procedures, for the qualitative detection of Histoplasma antigens as an aid in the diagnosis of histoplasmosis.

Procedure

The ALPHA Histoplasma Antigen EIA is an immunoenzymatic, sandwich microplate assay which detects antigens in urine and serum specimens. Rabbit anti-Histoplasma IgG antibodies bound to microwell plates are used as capture antibodies, and biotinylated rabbit anti-Histoplasma IgG antibodies are used as detect antibodies. This test has been cleared or approved for diagnostic use by the U.S. Food and Drug Administration in urine specimens only.

Specificity

The Alpha Histoplasma AG EIA was found to cross-react with Blastomyces dermatiditis, Coccidioides immitis, and Paracoccidioides brasiliensis in urine and serum. Although not tested in the Alpha Histoplasma AG EIA, Penicillium marneffei is known to cross-react with Histoplasma antibodies. The assay was not cross-reactive with Candida albicans, Cryptococcus neoformans or Aspergillus spp. in urine or serum.

Assay Range

The reference range is < 2.0 EIA units. Numerical values will be reported.

Patients with EIA values ≥ 2.0 units are considered positive.

Patients with EIA values < 2.0 units are considered negative.

A reference EIA unit value of less than 2.0 has been established for urine. Clinical studies performed in other laboratories support use of the same reference interval in serum samples for Histoplasma antigen EIA assays.

Assay Limitations

This test is used for the qualitative detection of Histoplasma antigens in specimens. The magnitude of the measured result, above the cut off, is not indicative of the total amount of antigen present. A negative result does not preclude diagnosis of histoplasmosis. The Alpha Histoplasma Antigen EIA is not intended for monitoring therapy. The performance of the ALPHA Histoplasma Ag EIA is unknown when specimens including the following substances are tested: foods which produce color in urine, vaginal cream, caffeine, ascorbic acid, itraconazole, amphotericin B, acetaminophen, or acetylsalicylic acid. The ALPHA Histoplasma Ag EIA was not evaluated in pediatric specimens. Testing should not be performed as a screening procedure for the general population. The predictive value of a positive or negative result depends on the prestest likelihood of histoplasmosis disease being present. Testing should only be done when clinical evidence suggests the diagnosis of histoplasmosis disease. Specimens should be repeated if the results are positive and inconsistent with clinical findings. Results between different Histoplasma capsulatum antigen assays cannot be compared.

Causes For Rejection

Specimens other than than those listed. Specimens older than 14 days. Specimens received not frozen. Specimens that have been stored at ambient temperature. Specimens that have been stored at 2 to 8°C for longer than 5 days. If storage longer than 5 days is needed, samples should be frozen at -20°C or colder. Unless indicated as stored frozen, the specimen will be rejected if the draw date is >5 days from receipt at Viracor-IBT.

Turnaround Time

Same day as specimen received. Monday through Saturday.

Shipping

Ship Monday through Friday. Friday shipments must be labeled for Saturday delivery. All specimens must be labeled with patient's name and collection date. A Viracor-IBT test requisition form must accompany each specimen. Ship specimens FedEx Priority Overnight to: Viracor-IBT Laboratories, 1001 NW Technology Dr, Lee's Summit, MO 64086.

Specimen Information

3702 urine

NY approved. Collect 2 mL sample in a sterile urinalysis container then transfer to sterile, screw top tube for shipment. Ship on dry ice Monday through Friday. Samples can be stored for up to 5 days at 2 to 8 °C. If storage longer than 5 days is needed, samples should be frozen at -20°C or colder for up to 14 days.

3710 serum

NY approved. Collect 3-5 mL blood specimen in a gel separator tube (SST) without anti-coagulants. Allow specimen to clot, then centrifuge specimen within 2 hours of draw to pellet cells below the gel. Minimum volume is 1 mL serum following centrifugation. Specimen can be stored refrigerated at 2 to 8°C for up to 5 days or preferably stored frozen in a non-self defrosting freezer and shipped on dry ice for overnight delivery to Viracor-IBT Laboratories.

Disclaimer

Specimens are approved for testing in New York only when indicated in the Specimen Information field above.

The CPT codes provided are based on Viracor-IBT's interpretation of the American Medical Association's Current Procedural Terminology (CPT) codes and are provided for informational purposes only. CPT coding is the sole responsibility of the billing party. Questions regarding coding should be addressed to your local Medicare carrier. Viracor-IBT assumes no responsibility for billing errors due to reliance on the CPT codes illustrated in this material.

 

References

 

  1. Cox, M., G. Pesek, D. Phan, and G. Woods. Utility of a Histoplasma capsulatum Enzyme Immunoassay for Diagnosis of Disseminated Histoplasmosis and Correlation With Disease Activity. Arch Pathol Lab Med. 2008;132:1512.
  2. Gomez, B.L., J. I. Figueroa, A. J. Hamilton, B. L. Ortiz, M. A. Robledo, A. Restrepo, and R. J. Hay. Development of a novel antigen detection test for histoplasmosis. J Clin Microbiol. 1997;35:2618-2622.
  3. Kauffman, C. A. Diagnosis of histoplasmosis in immunosuppressed patients.  Curr Opin Infect Dis. 2008;21:421-425.
  4. Kauffman, C. A. Histoplasmosis: a clinical and laboratory update. Clin Microbiol.  2007;Rev. 20:115-132.
  5. Wheat, J. 1994. Histoplasmosis: recognition and treatment. Clin Infect Dis.  1994;19(suppl)1:S19-S27.
  6. Yeo, S. F. and B. Wong. Current status of nonculture methods for diagnosis of invasive fungal infections. Clin Microbiol Rev.  2002;15:465-484.

 

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