Dr KK
Aggarwal
Do not use
negative serology as a reliable indicator of mucosal healing in patients with
celiac disease who have persistent symptoms. Instead perform endoscopic
biopsies to evaluate healing, recommends the American Gastroenterological
Association (AGA) in a clinical practice update on the role of serology and
histology in monitoring celiac disease.
The key
recommendations are:
·
Serology is a crucial component of the detection
and diagnosis of CD, particularly tissue transglutaminase-immunoglobulin A
(TG2-IgA), IgA testing, and less frequently, endomysial IgA testing.
·
Thorough histological analysis of duodenal biopsies
with Marsh classification, counting of lymphocytes per high-power field, and morphometry
is important for diagnosis and for differential diagnosis. A strongly
positive TG2-IgA combined with a positive endomysial antibody in a second blood
sample increases the positive predictive value for CD to virtually 100%.
·
Negative IgA isotype testing despite strong
suspicion may be explained by IgA deficiency. Measuring total IgA levels, IgG
deamidated gliadin antibody tests, and TG2-IgG testing in such cases.
·
IgG isotype testing for TG2 antibody is not
specific in the absence of IgA deficiency.
·
In patients found to have CD first by intestinal
biopsies, confirm by celiac-specific serology before starting gluten-free diet
(GFD).
·
In patients with strong suspicion of CD but
negative biopsies, TG2-IgA should still be performed and, if positive, repeat
biopsies might be considered either at that time or sometime in the future.
·
Reduction or avoidance of gluten before diagnostic
testing is discouraged, as it may reduce the sensitivity of both serology and
biopsy testing.
·
When patients have already started on a GFD before
diagnosis, the patient are suggested to go back on a normal diet with 3 slices
of wheat bread daily preferably for 1 to 3 months before repeat determination
of TG2-IgA.
·
HLA-DQ2/DQ8 has a limited role in diagnosis. Its value is largely related to its
negative predictive value to rule out CD in patients who are seronegative in
the face of histologic changes, in patients who did not have serologic
confirmation at the time of diagnosis, and in those patients with a historic
diagnosis of CD; especially as very young children before the introduction of
celiac-specific serology.
·
Celiac serology has a guarded role in the detection
of continued intestinal injury, in particular as to sensitivity, as negative
serology in a treated patient does not guarantee that the intestinal mucosa has
healed. Persistently positive serology usually indicates ongoing intestinal
damage and gluten exposure. Follow-up serology should be performed 6 and 12
months after diagnosis, and then every year.
·
Patients with persistent or relapsing symptoms,
without other obvious explanations for those symptoms, should undergo
endoscopic biopsies to determine healing even in the presence of negative
TG2-IgA.
(Source: Husby S, et al. AGA
Clinical Practice Update on diagnosis and monitoring of celiac disease-changing
utility of serology and histologic measures: expert review. Gastroenterology.
2019;156(4):885-89).
Dr KK Aggarwal
Padma Shri Awardee
President Elect Confederation of
Medical Associations in Asia and Oceania
(CMAAO)
Group Editor-in-Chief IJCP Publications
President Heart Care Foundation of
India
Past National President
IMA
