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Test Code GASCA Saccharomyces cerevisiae Antibody, IgG, Serum

Performing Laboratory

Mayo Medical Laboratories in Rochester

Reporting Name

Saccharomyces cerevisiae Ab, IgG, S

Specimen Type

Serum


Specimen Required


Container/Tube: 

Preferred: Serum gel

Acceptable: Red top

Specimen Volume: 0.50 mL


Reject Due To

Hemolysis

Mild OK; Gross reject

Lipemia

Mild OK; Gross reject

Icterus

Mild OK; Gross OK

Other

NA

Specimen Stability Information

Specimen Type Temperature Time
Serum Refrigerated (preferred) 21 days
  Frozen  21 days

Specimen Minimum Volume

0.4 mL

Day(s) and Time(s) Performed

Monday through Friday; 5 p.m.

Specimen Retention Time

7 days

Analytic Time

Same day/1 day

Reference Values

Negative: ≤20.0 U

Equivocal: 20.1-24.9 U

Weakly positive: 25.0-34.9 U

Positive: ≥35.0 U

Reference values apply to all ages.

Useful For

Helping clinicians distinguish between ulcerative colitis and Crohn's disease in patients suspected of having inflammatory bowel disease

Method Name

Enzyme-Linked Immunosorbent Assay (ELISA)

Test Classification

This test has been cleared or approved by the U.S. Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.

CPT Code Information

86671

LOINC Code Information

Test ID Test Order Name Order LOINC Value
GASCA Saccharomyces cerevisiae Ab, IgG, S 47321-5

 

Result ID Test Result Name Result LOINC Value
GASCA Saccharomyces cerevisiae Ab, IgG, S 47321-5

Clinical Information

Inflammatory bowel disease (IBD) refers to 2 diseases, ulcerative colitis (UC) and Crohn's disease (CD), which produce inflammation of the large or small intestines.(1) The diagnoses of both diseases are based on clinical features, radiographic findings, colonoscopy, mucosal biopsy histology, and, in some cases, operative findings and resected bowel pathology and histology.

 

Patients with IBD have also been shown to have antibodies in serum that help distinguish between CD and UC.(2) Patients with UC often have measurable neutrophil-specific antibodies (NSA) that react with as yet uncharacterized target antigens in human neutrophils; whereas patients with CD often have measurable antibodies of the IgA and/or IgG isotypes that react with cell wall mannan of Saccharomyces cerevisiae strain Su 1.

Interpretation

In IBDP / Inflammatory Bowel Disease Serology Panel, Serum, anti-Saccharomyces cerevisiae antibodies (ASCA) and neutrophil-specific antibodies (NSA) are measured. The finding of NSA with normal levels of IgA and IgG ASCA is consistent with the diagnosis of ulcerative colitis (UC); the finding of negative NSA with elevated IgA and IgG ASCA is consistent with Crohn's disease (CD).

 

NSA are detectable in approximately 50% of patients with UC.

 

Elevated levels of either IgA or IgG ASCA occur in approximately 55% of patients with CD. Elevated levels of both IgA and IgG ASCA occur in approximately 40% of patients with CD.

 

Employed together, the tests for NSA and ASCA have the following positive predictive values (PPV) for UC and CD, respectively:(2)

-NSA-positive with normal levels of IgA and IgG ASCA, PPV of 91%

-NSA-negative with elevated levels of IgA and IgG ASCA, PPV of 90%

Cautions

IBDP / Inflammatory Bowel Disease Serology Panel, Serum is useful as an adjunct in the diagnosis of ulcerative colitis (UC) and Crohn's disease (CD), but should not be relied upon exclusively to establish the diagnosis or to distinguish between these 2 diseases. Some patients with CD have detectable neutrophil-specific antibodies (NSA), and some patients with UC have elevated levels of IgA and/or IgG anti-Saccharomyces cerevisiae antibodies (ASCA).

 

Measurement of ASCA and NSA are not useful to determine the extent of disease in patients with inflammatory bowel disease or to determine the response to disease-specific therapy including surgical resection of diseased intestine.

Clinical Reference

1. The Autoimmune Diseases: Inflammatory Bowel Diseases. Edited by NR Rose, IR Mackay. New York, NY, Elsevier Academic Press, 2008

2. Sandborn WJ, Loftus EV Jr, Homburger HA, et al: Evaluation of serological disease markers in a population-based cohort of patients with ulcerative colitis and Crohn's disease. Inflamm Bowel Dis 2001 Aug;7(3):192-201

Method Description

IgG anti-Saccharomyces cerevisiae antibodies (ASCA) are measured by commercial, microtiter enzyme immunoassays (INOVA Diagnostics, San Diego, CA). This assay uses polystyrene microtiter plates coated with partially purified Saccharomyces cerevisiae antigens to capture antibodies from patient's sera and horseradish peroxidase-conjugated anti-IgG antibodies to detect IgG ASCA. Results of the test for IgG ASCA are reported in arbitrary units.(Package insert: QUANTA LITE ASCA [Saccharomyces cerevisiae] IgG ELISA 708865)

Forms

If not ordering electronically, complete, print, and send a Gastroenterology and Hepatology Test Request Form (T728) with the specimen (http://www.mayomedicallaboratories.com/it-mmfiles/gastroenterology-and-hepatology-test-request.pdf)