Anti-Saccharomyces cerevisiae Antibodies (ASCA)

Also Known As

Anti-Saccharomyces cerevisiae mannan antibodies

Formal Name

Saccharomyces cerevisiae Antibodies, IgG or IgA

This article was last reviewed on

January 22, 2019.

This article waslast modified on February 19, 2019.

At a Glance

Why Get Tested?

To help distinguish between Crohn disease (CD) and ulcerative colitis (UC), the two most common types of inflammatory bowel disease (IBD); as an adjunct to other IBD testing

When To Get Tested?

When you have symptoms such as persistent or intermittent diarrhea and abdominal pain that your healthcare practitioner suspects may be due to an IBD; when your healthcare practitioner wants to distinguish between CD and UC

Sample Required?

A blood sample drawn from a vein in your arm

Test Preparation Needed?

None

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The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

What is being tested?

Anti-Saccharomyces cerevisiae antibodies (ASCA) are immune proteins that are frequently present in people who have inflammatory bowel disease (IBD). This test detects ASCA in the blood.

S. cerevisiae are common yeast found in various foods. The correlation between the presence of antibodies to S. cerevisiae and their involvement in the inflammatory bowel disease process is not understood at this time.

IBD is a group of chronic disorders, thought to be due to an autoimmune process, characterized by swollen and damaged tissues in the lining of the intestinal tract. The symptoms and severity of IBD vary from person to person and may fluctuate over time. Many of those affected experience flare-ups followed by periods of lessened symptoms or even remission.

The two most common types of IBD are Crohn disease (CD) and ulcerative colitis (UC). CD can affect any part of the intestinal tract, from mouth to anus, but is primarily found in the small intestine and/or in the colon, while UC occurs in the colon.

The diagnosis of CD or UC is usually made on the basis of endoscopic testing and the examination of biopsy samples from the intestines. Because both CD and UC can be found in the colon, even using biopsies it can sometimes be difficult to distinguish between the two. When this occurs, ASCA testing may be helpful as ASCA is much more frequently found in people with CD than in those with UC.

There are two classes of Saccharomyces cerevisiae antibodies produced by the body, ASCA IgG and ASCA IgA. Testing usually includes both classes. ASCA IgG may predict the severity of the disease and the need for surgery as a treatment option.

Common Questions

How is the test used?

The test for anti-Saccharomyces cerevisiae antibodies (ASCA) is used to help distinguish between Crohn disease (CD) and ulcerative colitis (UC), the two most common types of inflammatory bowel disease (IBD). Testing usually includes detecting two different classes of ASCA in the blood, IgG and IgA.

IBDs are primarily diagnosed through non-laboratory evaluations, such as a biopsy of the intestine. In some cases, however, it can be difficult to distinguish between CD and UC. An ASCA test is often ordered along with a test for perinuclear anti-neutrophil cytoplasmic antibody (pANCA) to help determine which type of IBD a person has. The presence of ASCA is more common in CD, while pANCA is more common in UC. Other antibody tests may also be used in combination with ASCA testing, such as anti-CBir1 (anti-flagellin antibody) and anti-Omp C (anti-outer membrane protein antibody).
When is it ordered?
ASCA testing is primarily ordered when a person has signs and symptoms that suggest IBD and a healthcare practitioner is attempting to distinguish between CD and UC.

Signs and symptoms of an IBD may include:

Abdominal pain and cramps

Diarrhea

Rectal bleeding

Fever

Fatigue

Joint, skin, bone and organ-related symptoms

Delayed development and growth retardation in children
What does the test result mean?
A positive ASCA result is not diagnostic of CD, UC, or of an IBD, but it does make it more likely that a person with symptoms has an IBD.

Results of ASCA testing are often interpreted in conjunction with the results of pANCA testing:

If ASCA is positive and pANCA is negative, then it is likely that the person has CD.

If ASCA is negative and pANCA is positive, then it is likely that the person has UC.

A negative result for ASCA and pANCA does necessarily rule out IBD. A person with negative test results may still have CD, UC, or another IBD.

The presence of multiple antibodies (ASCA, anti-CBir1, anti-Omp C) may indicate the likelihood of a more aggressive disease, but negative results do not rule out aggressive disease.
Besides ASCA, what other testing may be done?

In some cases, several antibody tests, including ASCA, perinuclear anti-neutrophil cytoplasmic antibody (pANCA), anti-CBir1 (anti-flagellin antibody), and anti-Omp C (anti-outer membrane protein antibody), may be ordered together as a panel and the overall findings evaluated to either help distinguish between CD and UC or to try to help determine a prognosis for a person's CD. The presence of Anti-CBir1 and anti-Omp C are indicative of CD. The presence of multiple antibodies may indicate the likelihood of a more aggressive disease, but negative results do not rule out aggressive disease.

Since the symptoms associated with IBD may be seen with a number of conditions, other tests are frequently performed prior to or along with ASCA testing to rule out other causes for the symptoms. For more on this, see the article on Inflammatory Bowel Disease.
Is there anything else I should know?

The amount of ASCA present may not correlate with the severity of a person's symptoms or condition and it cannot be used to monitor response to treatment.
Is it necessary to perform ASCA testing more than once?

Testing is usually only performed once, to help distinguish between CD and UC. Once a decision has been made, there is generally no need for repeat testing. It is typical to order tests for the two classes of antibody, ASCA IgG and ASCA IgA, at the same time. However, if only one of the types was initially ordered, then the other type (or more likely both) may be ordered at a later date.
Will ASCA go away once they have developed?

The level of antibody may vary over time, but once a person's body has produced ASCA, it will continue to be present.
How long will it take for my results?

ASCA testing is not offered by every hospital laboratory. It may be necessary to send your blood sample to a reference laboratory for testing and it may take from one day to several days for your results to be available.

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View Sources

Sources Used in Current Review

(2018 March 22, Updated). Inflammatory bowel disease (IBD). Centers for Disease Control and Prevention. Available online at https://www.cdc.gov/ibd/what-is-ibd.htm. Accessed on 10/05/18.

Ghazi, L. (2017 January 6, Updated). Crohn Disease. Medscape Gastroenterology. Available online at https://emedicine.medscape.com/article/172940-overview. Accessed on 10/05/18.

Rowe, W. and Lichtenstein, G. (2017 October 18, Updated). Inflammatory Bowel Disease. Medscape Gastroenterology. Available online at https://emedicine.medscape.com/article/179037-overview. Accessed on 10/05/18.

Couturier, M. et. al. (2018 July, Updated). Inflammatory Bowel Disease – IBD. ARUP Consult. Available online at https://arupconsult.com/content/inflammatory-bowel-disease. Accessed on 10/05/18.

Wang, Z. et. al. (2017 April 6). Serologic testing of a panel of five antibodies in inflammatory bowel diseases: Diagnostic value and correlation with disease phenotype. Biomed Rep. 2017 Apr;6(4):401-410. doi: 10.3892/br.2017.860. Epub 2017 Feb 17. Available online at https://www.ncbi.nlm.nih.gov/pubmed/28413638. Accessed on 10/05/18.

(© 1995–2018). Inflammatory Bowel Disease Serology Panel, Serum. Mayo Clinic Mayo Medical Laboratories. Available online at https://www.mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/81443. Accessed on 10/05/18.

Sources Used in Previous Reviews

Ananthakrishnan, A. (2013). Personalizing Therapy for Inflammatory Bowel Diseases. Medscape Multispecialty from Expert Rev Gastroenterol Hepatol. 2013;7(6):549-558. [On-line information]. Available online at http://www.medscape.com/viewarticle/810751. Accessed March 2014.

Ghazi, L. (Updated 2014 January 13). Crohn Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/172940-overview. Accessed March 2014.

Rowe, W. and Lichtenstein, G. (Updated 2013 November 25). Inflammatory Bowel Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/179037-overview. Accessed March 2014.

Grossman, A. and Mamula, P. (Updated 2013 October 14). Pediatric Crohn Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/928288-overview. Accessed March 2014.

Basson, M. (Updated 2013 May 27). Ulcerative Colitis. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/183084-overview. Accessed March 2014.

(Updated 2013 December 17). Anti-Saccharomyces Cerevisiae Antibodies, IgA and IgG. The University of Iowa Department of Pathology LABORATORY SERVICES HANDBOOK [On-line information]. Available online at http://www.healthcare.uiowa.edu/path_handbook/handbook/test1155.html. Accessed March 2014.

Minerva, P. (Updated 2012 March 29). Enteropathic Arthropathies. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/334746-overview. Accessed March 2014.

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(Updated 2014 February). Inflammatory Bowel Disease – IBD. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/IBD.html?client_ID=LTD#tabs=0. Accessed March 2014.

Ryan, J. D. et. al. (2013). Predicting Complicated Crohn's Disease and Surgery. Medscape Multispecialty from Aliment Pharmacol Ther. 2013;38(3):274-283. [On-line information]. Available online at http://www.medscape.com/viewarticle/807728. Accessed March 2014.

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(2011 December). Crohn's Disease. National Digestive Diseases Information Clearinghouse (NDDIC) [On-line information]. Available online at http://digestive.niddk.nih.gov/ddiseases/pubs/crohns/. Accessed March 2014.

(Updated 2011 April 30). Diagnosing and Managing IBD. Crohn's & Colitis Foundation of America [On-line information]. Available online at http://www.ccfa.org/resources/diagnosing-and-managing-ibd.html. Accessed March 2014.

Yau, Y. et. al. (2013). Proteomics and Metabolomics in Inflammatory Bowel Disease. Medscape Multispecialty from J Gastroenterol Hepatol. 2013;28(7):1076-1086. [On-line information]. Available online at http://www.medscape.com/viewarticle/807024. Accessed March 2014.

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