Specimen:

Serum

Collection Medium:

Minimum:

Adult - 5 mL; red top tube
Pediatric - 2 mL; red top tube

Testing
Schedule:

Weekly

Analytic Time:

1 week

Reference Range:

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

Comments:

ASCA testing may be clinically useful in the evaluation of suspected 
inflammatory bowel disease, including Crohn's disease and ulcerative 
colitis (UC). ASCA is significantly more prevelant in Crohn's disease 
than in UC or in healthy individuals.

Published studies of Crohn's disease have reported IgG ASCA test 
sensitivity for CD is about 74% while IgA ASCA is about 49% 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 ASCA's 
are positive. There are published reports of 95-100% specificity with 
dual IgG and IgA 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.

Methodology:

Enzyme-Linked Immunosorbent Assay Test (ELISA)

Sample
Processing:

Centrifuge at 3500 RPM for 5 minutes.
Aliquot serum into labeled container and cap.
Relevant clinical information must be submitted with specimen in order 
to provide correct interpretation of test results.

Sample
Storage:

Refrigerate serum 2-8 degree C.

Transport
Instructions:

Place specimen into zip-lock type bag, seal bag.
Place requisition into outside pocket of bag.
Ship at ambient temperature.