Test Catalog

Test Id : HSTQU

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Histoplasma Antigen, Quantitative Enzyme Immunoassay, Random, Urine

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Overview

Test Catalog

Useful For
Suggests clinical disorders or settings where the test may be helpful

Aiding in the diagnosis of Histoplasma capsulatum infection

 

Monitoring Histoplasma antigen levels in urine

Highlights

Alongside other routine methods including culture, molecular testing, and serology, this test aids in the diagnosis of infection with Histoplasma capsulatum.

Method Name
A short description of the method used to perform the test

Enzyme Immunoassay (EIA)

NY State Available
Indicates the status of NY State approval and if the test is orderable for NY State clients.

Yes

Reporting Name
Lists a shorter or abbreviated version of the Published Name for a test

Histoplasma Ag, Quant EIA, U

Aliases
Lists additional common names for a test, as an aid in searching

HSTQU

Histo

Histoplasma capsulatum

Histoplasma galactomannan antigen

Histoplasma polysaccharide

Specimen Type
Describes the specimen type validated for testing

Urine

Specimen Required
Defines the optimal specimen required to perform the test and the preferred volume to complete testing

Supplies: Sarstedt 5 mL Aliquot Tube (T914)

Container/Tube: Plastic vial

Specimen Volume: 4 mL

Collection Instructions:

1. Collect a random urine specimen.

2. No preservative.

3. Do not centrifuge to remove particulates.

Forms

If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.

Specimen Minimum Volume
Defines the amount of sample necessary to provide a clinically relevant result as determined by the Testing Laboratory

2.5 mL

Reject Due To
Identifies specimen types and conditions that may cause the specimen to be rejected

Gross hemolysis Reject
Turbid
Colored 		Reject
 

Specimen Stability Information
Provides a description of the temperatures required to transport a specimen to the performing laboratory, alternate acceptable temperatures are also included

Specimen Type Temperature Time Special Container
Urine Refrigerated (preferred) 14 days
Frozen 31 days
Ambient 72 hours

Useful For
Suggests clinical disorders or settings where the test may be helpful

Aiding in the diagnosis of Histoplasma capsulatum infection

 

Monitoring Histoplasma antigen levels in urine

Clinical Information
Discusses physiology, pathophysiology, and general clinical aspects, as they relate to a laboratory test

Histoplasma capsulatum is a dimorphic fungus endemic to the Midwestern United States, particularly along the Mississippi River and Ohio River valleys. Infection occurs following inhalation of fungal microconidia, and subsequent clinical manifestations are largely dependent on the fungal burden at the time of exposure and the patient's underlying immune status. While the vast majority (>90%) of exposed individuals will remain asymptomatic, individuals seeking medical attention can present with a diverse set of symptoms ranging from a self-limited pulmonary illness to severe, disseminated disease. Individuals at risk for severe infection include those with impaired cellular immunity, who have undergone organ transplantation, who are HIV positive, or who have a hematologic malignancy.

 

The available laboratory methods for the diagnosis of H capsulatum infection include fungal culture, molecular techniques, serologic testing, and antigen detection. While culture remains the gold standard diagnostic test and is highly specific, prolonged incubation is often required, and sensitivity decreases (9%-34%) in cases of acute or localized disease. Similarly, molecular methods offer high specificity but decreased sensitivity. Serologic testing likewise offers high specificity; however, results may be falsely negative in immunosuppressed patients or those who present with acute disease. Also, antibodies may persist for years following disease resolution, thereby limiting the clinical specificity.

 

Detection of H capsulatum antigen from urine samples has improved sensitivity (80%-95%) for the diagnosis of active histoplasmosis compared to both culture and serology. Additionally, urine antigen levels can be followed to monitor patient response to therapy, with declining levels consistent with disease resolution. Notably, however, H capsulatum antigen may persist at low levels following completion of antifungal therapy and clinical improvement.

Reference Values
Describes reference intervals and additional information for interpretation of test results. May include intervals based on age and sex when appropriate. Intervals are Mayo-derived, unless otherwise designated. If an interpretive report is provided, the reference value field will state this.

HISTOPLASMA ANTIGEN RESULT:

Not Detected

 

HISTOPLASMA ANTIGEN VALUE

Not Detected

Detected: <0.2 ng/mL

Detected: 0.2-25.0 ng/mL

Detected: >25.0 ng/mL

Interpretation
Provides information to assist in interpretation of the test results

Not Detected: No Histoplasma antigen detected. False-negative results may occur. Repeat testing on a new specimen should be considered if clinically indicated.

 

Detected, <0.2 ng/mL: Histoplasma antigen detected below the limit of quantification (<0.2 ng/mL). Results should be correlated with clinical presentation, exposure history and other diagnostic procedures, including culture, serology, histopathology, and radiographic findings. False-positive results may occur in patients with other fungal infections, including Blastomyces.

 

Detected: Histoplasma antigen detected. The reportable range of this assay is 0.2 to 25.0 ng/mL. Results should be correlated with clinical presentation, exposure history, and other diagnostic procedures, including culture, serology, histopathology, and radiographic findings. False-positive results may occur in patients with other fungal infections, including Blastomyces.

 

Detected, >25 ng/mL: Histoplasma antigen detected above the limit of quantification (>25.0 ng/mL). Results should be correlated with clinical presentation, exposure history, and other diagnostic procedures, including culture, serology, histopathology, and radiographic findings. False-positive results may occur in patients with other fungal infections, including Blastomyces.

Cautions
Discusses conditions that may cause diagnostic confusion, including improper specimen collection and handling, inappropriate test selection, and interfering substances

Cross-reactivity with other fungal infections, including Blastomyces dermatitidis, may occur. Positive results should be correlated with other clinical and laboratory findings (eg, culture, serology).

 

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

 

Turbid urine specimens, containing excess protein, cells, or particulate matter, can inhibit the function of the test.

Clinical Reference
Recommendations for in-depth reading of a clinical nature

1. Theel ES, Harring JA, Dababneh AS, Rollins LO, Bestrom JE, Jespersen DJ: Reevaluation of commercial reagents for detection of Histoplasma capsulatum antigen in urine. J Clin Micrbiol. 2015 Apr;53(4):1198-1203. doi: 10.1128/JCM.03175-14

2. Wheat LJ, Freifeld AG, Kleiman MB, et al: Clinical practice guidelines for the management of patients with histoplasmosis: 2007 update by the Infectious Diseases Society of America. Clin Infect Dis. 2007 Oct 1;45(7):807-825

Method Description
Describes how the test is performed and provides a method-specific reference

The IMMY Clarus Histoplasma GM Enzyme Immunoassay (EIA) is an immunoenzymatic, sandwich microplate assay which detects Histoplasma galactomannan in urine. Galactomannan is a polysaccharide found in the cell wall. Monoclonal anti-Histoplasma IgG antibodies bound to microwell plates are used as capture antibodies. Horseradish peroxidase (HRP) conjugated anti-Histoplasma monoclonal IgG antibodies are used as detection reagents. Urine specimens are run untreated. The samples are added to the microwells coated with the capture antibodies and incubated.

 

If the patient specimen contains Histoplasma galactomannan, those antigens will become bound to the capture antibodies on the microwells. After incubation, the microwells are washed to remove unbound patient material. HRP detection antibodies are added to the microwells. After a second incubation, the microwells are washed to remove any unbound HRP detection antibodies. If antigen is present in the patient sample, a blue color develops with the addition of 3,3’,5,5’ tetramethylbenzidine (TMB). The reaction is stopped by the addition of a stop solution, where a yellow color develops. The optical density (absorbance) is checked with a microplate reader at 450 nm and a reference wavelength of 620/630 nm.(Package insert: Clarus Histoplasma GM Enzyme Immunoassay. IMMY; Rev. 0 05/08/2019)

PDF Report
Indicates whether the report includes an additional document with charts, images or other enriched information

No

Day(s) Performed
Outlines the days the test is performed. This field reflects the day that the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time before the test is performed. Some tests are listed as continuously performed, which means that assays are performed multiple times during the day.

Monday through Sunday

Report Available
The interval of time (receipt of sample at Mayo Clinic Laboratories to results available) taking into account standard setup days and weekends. The first day is the time that it typically takes for a result to be available. The last day is the time it might take, accounting for any necessary repeated testing.

Same day/1 to 3 days

Specimen Retention Time
Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded

14 days

Performing Laboratory Location
Indicates the location of the laboratory that performs the test

Rochester

Fees
Several factors determine the fee charged to perform a test. Contact your U.S. or International Regional Manager for information about establishing a fee schedule or to learn more about resources to optimize test selection.

  • Authorized users can sign in to Test Prices for detailed fee information.
  • Clients without access to Test Prices can contact Customer Service 24 hours a day, seven days a week.
  • Prospective clients should contact their account representative. For assistance, contact Customer Service.

Test Classification
Provides information regarding the medical device classification for laboratory test kits and reagents. Tests may be classified as cleared or approved by the US Food and Drug Administration (FDA) and used per manufacturer instructions, or as products that do not undergo full FDA review and approval, and are then labeled as an Analyte Specific Reagent (ASR) product.

This test has been modified from the manufacturer's instructions. Its performance characteristics were determined by Mayo Clinic in a manner consistent with CLIA requirements. This test has not been cleared or approved by the US Food and Drug Administration.

CPT Code Information
Provides guidance in determining the appropriate Current Procedural Terminology (CPT) code(s) information for each test or profile. The listed CPT codes reflect Mayo Clinic Laboratories interpretation of CPT coding requirements. It is the responsibility of each laboratory to determine correct CPT codes to use for billing.

CPT codes are provided by the performing laboratory.

87385

LOINC® Information
Provides guidance in determining the Logical Observation Identifiers Names and Codes (LOINC) values for the order and results codes of this test. LOINC values are provided by the performing laboratory.

Test Id Test Order Name Order LOINC Value
HSTQU Histoplasma Ag, Quant EIA, U 48952-6
Result Id Test Result Name Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
HISTF Histoplasma Ag Result 44524-7
DEXUH Histoplasma Ag Value 48952-6

Test Setup Resources

Setup Files
Test setup information contains test file definition details to support order and result interfacing between Mayo Clinic Laboratories and your Laboratory Information System.

Excel | PHP Pdf | CMS Pdf

Sample Reports
Normal and Abnormal sample reports are provided as references for report appearance.

Normal Reports | Abnormal Reports

SI Sample Reports
International System (SI) of Unit reports are provided for a limited number of tests. These reports are intended for international account use and are only available through MayoLINK accounts that have been defined to receive them.

SI Normal Reports | SI Abnormal Reports