Of 26 subjects who were ASCA-positive and ANCA-negative, 8 had a final diagnosis of CD after 6 years follow- up, 2 had a final diagnosis of UC, and 16 remained with a diagnosis of indeterminate colitis.

Only 1 genotypic or phenotypic assay of TPMT activity is necessary per member per lifetime.

Aetna considers NUDT15 testing experimental and investigational for all other indications because its effectiveness for indications other than the one listed above has not been established.

Aetna considers fecal lactoferrin experimental and investigational for evaluation of infectious diarrhea, Clostridium difficile infection, and all other indications.

This panel has not been shown to have levels of specificity sufficient to distinguish ulcerative colitis (UC) from Crohns disease (CD) in indeterminate cases.

ANCA have also been found to be associated with Wegeners granulomatosis and other forms of systemic vasculitides, and more recently with sclerosing cholangitis and other autoimmune liver diseases.

Anti-Saccharomyces cerevisiae antibody (ASCA) is primarily detected in patients with CD; ASCA has been found to be detectable in 46 to 70 of patients with CD and 6 to 12 of patients with UC.

In a paper for the North American Society for Pediatric Gastroenterology and Nutrition, Griffiths concluded that the relatively low sensitivities of serology for Crohns disease and ulcerative colitis as documented in all studies argue against there being any greater value of ASCAANCA as routine or first-line screening tests for inflammatory bowel disease in comparison to clinical acumen and the equally sensitive (albeit less specific) measurement of acute phase reactants.

Moreover, the need for performance of definitive radiologic and endoscopic studies to guide therapy by defining the extent and nature of inflammatory bowel diseases (IBD) will not be averted by positive serologic tests.

Gupta et al (2004) examined the concordance of serologic testing for inflammatory bowel disease with clinical diagnosis established by traditional testing in children.

The investigators found that the sensitivity of serologic testing is insufficient to replace traditional studies when evaluating children for inflammatory bowel disease.

The investigators evaluated the results of ANCA and ASCA testing in 107 children who had serologic testing for inflammatory bowel disease (IBD) at their center, and compared these results with their clinical diagnosis.

The investigators calculated that the sensitivity, specificity, positive and negative predictive values of serologic testing for ulcerative colitis were 69.2, 95.1, 90.0 and 87.1, respectively, and for CD were 54.1, 96.8, 90.9 and 80.8 respectively.

The investigators concluded that the low sensitivity, especially for Crohns disease, precludes the possibility that the IBD Diagnostic System can replace traditional studies when evaluating for inflammatory bowel disease.

A number of studies have reported that IgA and IgG ASCA titers are significantly greater and highly specific for CD, and that and that pANCA positivity is highly specific for UC.

However, there is much less published information concerning the subgroup of IBD patients with colitis only, where differentiation of UC from CD is clinically problematic.

One investigator reported ASCA positivity in only 47 of 17 patients with Crohns colitis.

Another investigator found only 32 of 37 patients with Crohns colitis were ASCA positive and pANCA negative.

Conversely, studies have found that the majority of Crohns patients positive for pANCA have a UC-like presentations (Bentley et al, 2001; Ruemmele, 1998; Vasiliauskas et al, 1996).

Griffiths explained, hence, the usefulness of serology is less (where it is needed most), given the higher prevalence of pANCA positivity and the lower prevalence of ASCA positivity in CD confined to the colon.

Only a few patients have been studied, and follow-up is too limited.

In the only prospective study of serologic testing in indeterminate colitis, Joosens et al (2002) examined the results of serologic testing for ASCA or ANCA and final diagnosis of CD or UC after 6-year follow-up of 97 patients with indeterminate colitis.

The largest group (47) of subjects were negative for both ANCA and ASCA; 3 of these had a final diagnosis of CD, 4 had a final diagnosis of UC, and 40 had a final diagnosis of indeterminate colitis.

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