Trip Answers

Question answered:12/12/06 Warning! this question is over two years old.

We found a number of articles that discuss antibody screening in children.

 

A 2005 paper, published in Gastroenterology was a systematic review of the diagnostic performance of serologic tests for the diagnosis and screening of CD [1].  This reported:

 

“The pooled specificity of endomyseal antibody (EMA)-monkey esophagus (ME) or EMA-human umbilical cord (HU) was close to 100% in adults and children. The pooled specificity of transglutaminase antibody (tTG)-guinea pig (GP) and tTG-human recombinant (HR) were between 95% and 99%. IgA-EMA-ME demonstrated sensitivities of 96% and 97% in children and adults, respectively. EMA-HU demonstrated a similar sensitivity of 97% in children but 90% in adults. The pooled sensitivity of tTG-GP in adults and children was 90% and 93%, respectively. The sensitivity of tTG-HR was 98% and 96%, respectively. The performance of antigliadin antibody was inferior to that of EMA and tTG. EMA and tTG offer high sensitivity and specificity. The sensitivity of these tests appears to be lower than reported when milder histologic grades are used to define CD (below 90%). If true, the nearly perfect negative predictive value of these tests would drop. The positive predictive value of these tests is likely lower than reported when the tests are applied in low-prevalence populations.”

 

A 2005 American guideline reports on the diagnosis and management of celiac disease in children [2].  With regard to tests, it reports:

 

“Based on the current evidence and practical considerations, including accuracy, reliability, and cost, measurement of IgA antibody to human recombinant tissue transglutaminase (TTG) is recommended for initial testing for CD. Although as accurate as TTG, measurement of IgA antibody to endomysium (EMA) is observer dependent and therefore more subject to interpretation error and added cost. Because of the inferior accuracy of the antigliadin antibody tests (AGA), the use of AGA IgA and AGA IgG tests is no longer recommended for detecting CD.

 

Individuals with CD who are also IgA deficient will not have abnormally elevated levels of TTG IgA or EMA IgA. The occurrence of both CD and IgA deficiency in the same individual appears to be rare in asymptomatic individuals (approximately 1:8,500 of the general population) but is more likely in symptomatic children with CD (approximately 2%). Therefore, when testing for CD in children with symptoms suspicious for CD, measurement of quantitative serum IgA can facilitate interpretation when the TTG IgA is low. In individuals with known selective IgA deficiency and symptoms suggestive of CD, testing with TTG IgG is recommended. Even when serological tests for CD are negative, in children with chronic diarrhea or FTT and in those belonging to a group at risk (e.g., selective IgA deficiency or a positive family history of CD) who have symptoms compatible with CD, an intestinal biopsy can be helpful to identify the unusual case of seronegative CD or to detect other mucosal disorders accounting for the symptoms.”

 

The BMJ recently published a review of two commercial stool tests for detection of secretory IgA antibodies against gliadin and human tissue transglutaminase for diagnosis of coeliac disease in children with symptoms [3], this concluded:

 

“Neither stool test was suitable for screening for coeliac disease in children with symptoms.”

 

References

1) Rostom A et al. The diagnostic accuracy of serologic tests for celiac disease: a systematic review. Gastroenterology. 2005 Apr ; 128(4 Suppl 1): S38-46 (http://www.hubmed.org/display.cgi?uids=15825125)
2) North American Society for Pediatric Gastroenterology, Hepatology and Nutrition. Guideline for the diagnosis and treatment of celiac disease in children. 2005 (http://www.guideline.gov/summary/summary.aspx?doc_id=6819&nbr=4186&ss=6&xl=999)
3) Kappler M et al. Detection of secretory IgA antibodies against gliadin and human tissue transglutaminase in stool to screen for coeliac disease in children: validation study. BMJ  2006;332:213-214 (http://www.bmj.com/cgi/content/full/332/7535/213)
 

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