General Information: ASCA IgG and IgA-class ELISA testing is now available from the Immunopathology Laboratory. ASCA testing may be clinically useful in evaluation of suspected inflammatory bowel disease, including Crohn’s disease and ulcerative colitis (UC). ASCA is significantly more prevalent in Crohn’s disease than in UC or in healthy individuals. This has been independently validated in our laboratory in adult patients. Both IgA and IgG-class ASCA are available and we recommend that both be performed to obtain the best test specificity.

Sensitivity and Specificity: Published studies of Crohn’s disease have reported IgG ASCA test sensitivity for CD is about 76% while IgA ASCA is about 46% sensitive. About 25% of CD patients are repeatably negative for ASCA, therefore a negative result does not rule out CD.

The best specificity for CD is obtained when both IgG and IgA ASCAs are positive. There are published reports of 95-100% specificity with dual IgA and IgG positivity. Our own disease control testing (patients with a variety of GI and liver diseases) revealed 85% specificity with false positives in 1 patient with Mycobacterial granulomatous hepatitis, 1 patient with alcoholic hepatitis and 1 patient with acute colitis, probably UC.

Reference Ranges for IgG and IgA ASCA:

Negative	Equivocal	Positive
<20 units	20-24 units	>25 units

Turnaround Time: Testing will be performed weekly on Wednesdays.

Test Charge: $53.00 each.

Specimen Requirements: 5 ml red top tube

Further questions may be directed to: James A. Goeken, MD or Lisa A. Horning, MT (ASCP), SI