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Histoplasma Galactomannan EIA

Test Code: 30881/30882
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Clinical Utility

The clarus Histoplasma Galactomannan EIA (HGM201) is an immunoenzymatic, sandwich microplate assay used for the qualitative detection of Histoplasma galactomannan in serum samples.

About Histoplasma

Histoplasma capsulatum is a pathogenic dimorphic fungus of worldwide distribution endemic to the Ohio and Mississippi river valleys in the United States and to certain regions of Central and South Americas.1,5 The definitive diagnosis of histoplasmosis relies on the isolation of H. capsulatum by culture from clinical specimens.3,4 However, culture often requires a two- to four-week incubation period before the identification of the fungus is possible.6  Serological methods offer rapid alternatives to microbiological techniques; the detection of antibodies to H. capsulatum by immunodiffusion and complement fixation test is often used.4 However, anti-H. capsulatum antibody titers remain elevated months or even years after successful therapy, and as a result, it may not be possible to differentiate between sub-acute or inactive infections, chronic active forms, and relapses; the latter are particularly frequent among AIDS patients. In addition, false-negative results are often seen, as antibody titers may be low or even absent in immunocompromised patients and those with chronic disseminated disease.2 A more rational approach to the diagnosis of histoplasmosis and the follow-up of patients may be the detection of H. capsulatum antigen in body fluids.2

Procedure

The clarus Histoplasma Galactomannan EIA (HGM201) is an immunoenzymatic, sandwich microplate assay where monoclonal anti-Histoplasma IgG antibodies bound to microwell plates are used as capture antibodies. Serum or urine is added and any Histoplasma Galactomannan in the sample binds. Horseradish peroxidase (HRP) conjugated anti-Histoplasma monoclonal IgG antibodies are used as detection reagents.  The urine test has been registered with the FDA and is considered safe and effective for the detection of Histoplasma Galactomannan.  The performance characteristics of the serum assay were determined by Viracor Eurofins. It has not been approved or cleared by the US Food and Drug Administration.

Specificity

The clarus Histoplasma Galactomannan EIA was found to be cross-reactive with Paracoccidioides, Blastomyces, and some Candida specimens. Even though it was not tested in the clarus Histoplasma Galactomannan EIA, Talaromyces marneffei is known to cross-react with Histoplasma antibodies.

Same day (within 8 - 12 hours from receipt of specimen), Monday through Saturday.

Specimen Type Order Code CPT Code NY Approved Volume Assay Range Special Instructions
Serum 30881 87385 No

2 mL (min 0.5 mL)

The reference range is < 0.3 ng/mL.

Patients with values < 0.3 ng/mL are considered negative.

Patients with values ≥ 0.3 ng/mL and < 0.6 ng/mL are considered positive but below the limit of quantitation.

Patients with values between 0.6 - 25 ng/mL are considered positive.

Patients with values > 25 ng/mL are considered positive and above the limit of quantitation.

  • 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 0.5 mL serum following centrifugation.
  • Samples can be stored for up to 7 days ambient or 2 to 8 °C. If storage longer than 7 days is needed, samples should be frozen at -20°C or colder for up to 30 days.
  • Can be shipped ambient, refrigerated or frozen temperature Monday through Friday.
urine 30882 87385 Yes

2 mL (min 0.5 mL)

The reference range is < 0.3 ng/mL.

Patients with EIA values ≥ 0.3 ng/mL are considered positive.

Patients with EIA values < 0.3 ng/mL are considered negative.

  • Collect 2 mL (minimum 0.5 mL) sample in a sterile urinalysis container then transfer to sterile, screw top tube for shipment. 
  • Samples can be stored for up to 7 days ambient or at 2 to 8 °C. If storage longer than 7 days is needed, samples should be frozen at -20°C or colder for up to 30 days.
  • Can be shipped ambient, refrigerated or frozen temperature Monday through Friday.

Assay Limitations

  • A negative result does not preclude diagnosis of histoplasmosis.
  • The clarus Histoplasma Galactomannan EIA was found to be cross-reactive with Paracoccidioides, Blastomyces, and some Candida specimens. Positive tests should be confirmed in areas or patient groups where these organisms are endemic or a risk.
  • The clarus Histoplasma Galactomannan EIA is not intended for monitoring therapy.
  • Inadequate washing during the test procedure can cause excessive background reactivity.
  • The clarus Histoplasma Galactomannan EIA was not evaluated in pediatric specimens
  • The performance of the clarus Histoplasma Galactomannan EIA has not been established for manual reading and/or visual result determination.
  • 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 pretest likelihood of histoplasmosis disease being present. Testing should only be done when clinical evidence suggests the diagnosis of histoplasmosis.
  • Even though it was not tested in the clarus Histoplasma Galactomannan EIA, Talaromyces marneffei is known to cross-react with Histoplasma antibodies.
  • The performance of the clarus Histoplasma Galactomannan 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.
  • Results between different Histoplasma capsulatum assays cannot be compared.
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 Eurofins test requisition form must accompany each specimen. Ship specimens FedEx Priority Overnight to: Viracor Eurofins, 1001 NW Technology Dr, Lee's Summit, MO 64086.

Causes for Rejection

Specimens other than those listed. Specimens that have been stored at 2-8°C or ambient temperature for greater than 7 days. If storage longer than 7 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 >7 days from receipt at Viracor Eurofins.

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 Eurofins' 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 Eurofins 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. 2008. Utility of a Histoplasma capsulatum Enzyme Immunoassay for Diagnosis of Disseminated Histoplasmosis and Correlation With Disease Activity. Arch. Pathol. Lab Med 132:1512.
  2. Gomez, B. L., J. I. Figueroa, A. J. Hamilton, B. L. Ortiz, M. A. Robledo, A. Restrepo, and R. J. Hay. 1997. Development of a novel antigen detection test for histoplasmosis. J. Clin. Microbiol. 35:2618-2622.
  3. Kauffman, C. A. 2008. Diagnosis of histoplasmosis in immunosuppressed patients. Curr. Opin. Infect. Dis. 21:421-425.
  4. Kauffman, C. A. 2007. Histoplasmosis: a clinical and laboratory update. Clin. Microbiol. Rev. 20:115-132.
  5. Wheat, J. 1994. Histoplasmosis: recognition and treatment. Clin. Infect. Dis. 19 Suppl 1:S19-S27.
  6. Yeo, S. F. and B. Wong. 2002. Current status of nonculture methods for diagnosis of invasive fungal infections. Clin. Microbiol. Rev. 15:465-484.
  7. Cáceres DH, Samayoa BE, Medina NG, Tobón AM, Guzmán BJ, Mercado D, Restrepo A, Chiller T, Arathoon EE, Gómez BL. 2018. Multicenter validation of commercial antigenuria reagents to diagnose progressive disseminated histoplasmosis in people living with HIV/AIDS in two Latin American countries. J Clin Microbiol 56:e01959-17. https://doi.org/10.1128/JCM.01959-17.
  8. Product Insert, Clarus Histoplasma GM Enzyme Immunoassay. IMMY, 2019-05-08.

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