DESCRIPTION: Anti-Saccharomyces Cerevisiae Antibody (ASCA)
Saccharomyces cerevisiae (IgG)
Saccharomyces cerevisiae (IgA)
Helping clinicians distinguish between ulcerative colitis and Crohn’s disease in patients suspected of having inflammatory bowel disease. ASCA is significantly more prevalent in Crohn’s disease than in UC or in healthy individuals. A positive ASCA test is a useful adjunct to other clinical and laboratory findings to establish a diagnosis of Crohn’s Disease.
COLLECTION: Full Gold Top SST Tube (use serum collection tube in collection kit)
SPECIMEN STABILITY: Must be received within 24 hrs (Optimal) to 48 hrs of collection.
REJECTION CRITERIA: Hemolyzed, storage beyond temp/time limits, or plasma submitted
Enzyme immunoassay (EIA)
Results reported: NEGATIVE ⟨ 20 units, EQUIVOCAL 20.1 - 24.9 units, POSITIVE ⟩ 25 units
Antibodies to Saccharomyces cerevisiae are found in approximately 75% of patients with Crohn's disease, 15% of patients with ulcerative colitis, and 5% of the healthy population. High antibody titers increase the likelihood of disease, especially Crohn's disease, and are associated with more aggressive disease. As the inflammation in Crohn's disease is focused at the gut mucosa, most patients have IgA antibodies to S cerevisiae and half of these also have IgG antibodies. A minority of patients have only IgG antibodies to S cerevisiae.
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
DESCRIPTION: HLA Typing for Celiac Disease
HLA-DQ2.5, HLA-DQ8
SUB-COMPONENTS
(DQ2.5) DQA1*05 plus DQB1*02 (DQ8) DQA1*03 plus DQB1*0302
To determine genetic susceptibility to celiac disease (CD)
To rule out CD diagnosis
Certain human leukocyte antigen (HLA) alleles in the DQ region have been linked to a predisposition to CD. Approximately 95% of patients with CD have the HLA-DQ2 heterodimer determined by the DQA1*05 and DQB1*02 alleles, while close to 5% have the HLA-DQ8 heterodimer determined by the DQA1*03 and DQB1*0302 alleles.1 Since 25% to 40% of the United States population has either DQ2 or DQ8, the presence of either is not indicative of CD.1 Thus, the primary use of HLA-DQ typing is to rule out CD and determine the risk of susceptibility for CD.
COLLECTION: Whole blood in sodium citrate tube. (Use blue top tube included with collection kit)
SPECIMEN STABILITY: Stable at room temperature for 1 week.
REJECTION CRITERIA: Blood sample is over 1 week old; grossly hemolyzed, icteric, and lipemic specimens; improper anticoagulant used.
Real-time SSP-PCR (Polymerase Chain Reaction using Sequence Specific Primers) followed by melt curve analysis
A negative result for both HLA-DQ2 and HLA-DQ8 practically dismisses the diagnosis of CD and indicates an extremely low risk for subsequent development of the disease (≥95% negative predictive value). More than 97% of patients with celiac disease have either HLA-DQ2.5 or HLA-DQ8 genotype. Presence of either or both HLA-DQ2.5 and HLA-DQ8 does not mean CD will occur. In fact, the vast majority of people with the genes never develop CD. Having the genes may impact the risk of someday developing CD. On the other hand, if the genes are not present, the odds of developing CD are almost non-existent.
1. Megiorni F, Mora B, Bonamico M, Barbato M, Nenna R, et al: HLA-DQ and risk gradient for celiac disease. Hum Immunol 2009, 70:55-59.
DESCRIPTION: Deamidated Gliadin Peptide (DGP) Antibodies
Deaminated Gliadin Peptide Antibody- IgA Isotype
Deaminated Gliadin Peptide Antibody, IgG Isotype
This test offers better sensitivity and specificity than the original anti-gliadin antibody tests. It is a useful in the serologic diagnosis of celiac disease when the tTG antibody tests are low or negative, which can occur in young children and in individuals that are IgA deficient. The DGP antibodies can also be used to monitor gluten-free diet therapy.
COLLECTION: Full Gold Top SST Tube (use serum collection tube in collection kit)
SPECIMEN STABILITY: Must be received within 24 hrs (Optimal) to 48 hrs of collection
REJECTION CRITERIA: Hemolyzed, storage beyond temp/time limits, or plasma submitted
ELISA
Negative < 20 units: No antibody detected Weak Positive 20-30 units: Additional serologic testing, such as tTG antibodies, might be useful to help establish serologic evidence of celiac disease. Positive >30 units: Serologic evidence of celiac disease, confirm with other tests methods and clinical findings. Gluten restricted diet: Antibody levels should decrease or become undetectable after 6-12 months.
1. Pelkowski TD, Viera AJ: Celiac Disease:Diagnosis and Management. Am Fam Phys 2014:89(2) 99-105
2. Rubio-Tapia A, et al:ACG Clinical Guidelines: Diagnosis and Management of Celiac Disease. AM J Gastro 2013:108(5) 656-76.
DESCRIPTION: Tissue Transglutaminase (tTG) Antibodies
Tissue Transglutaminase Antibody - IgA Isotype
Tissue Transglutaminase Antibody - IgG Isotype
The tTG-IgA antibody test is currently considered as the test of choice for the serologic diagnosis and monitoring of celiac disease (1) , with sensitivity and specificity reported to be 95% or greater. The test is not useful, however, in individuals that have IgA deficiency, which is 10-15 times more common in celiac disease patients than the general population. In these instances, the tTG IgG test and DGP antibodies can be used in conjunction with a serum IgA determination to aid in evaluating these patients. The tTG antibodies can also be used to monitor gluten-free diet therapy.
COLLECTION Full Gold Top SST Tube (use serum collection tube in collection kit)
SPECIMEN STABILITY Must be received within 24 hrs (Optimal) to 48 hrs of collection.
REJECTION CRITERIA Hemolyzed, storage beyond temp/time limits, or plasma submitted
ELISA
Negative < 20 units: No antibody detected Weak Positive 20-30 units: Additional serologic testing, such as deaminated gliadin peptide (DGP), might be useful to help establish serologic evidence of celiac disease. Positive >30 units: Serologic evidence of celiac disease, confirm with other tests methods and clinical findings. Gluten restricted diet: Antibody levels of either or both tests should decrease or become undetectable after 6-12 months.
Pelkowski TD, Viera AJ: Celiac Disease:Diagnosis and Management. Am Fam Phys 2014:89(2) 99-105
Rubio-Tapia A, et al:ACG Clinical Guidelines: Diagnosis and Management of Celiac Disease. AM J Gastro 2013:108(5) 656-76.
Green PH, Cellier C: Celiac disease. N Engl J Med 2007;357:1731-1743
