Page 5 - 04- Celiac Disease

the diagnostic yield of celiac disease. Sampling of the duodenal bulb and the distal duodenum
is recommended to improve histologic confirmation of celiac disease.
IgA anti-tTG is the preferred serologic test in patients >2 years (1)[C].
Total serum IgA to screen for IgA deficiency

ALERT
Positive IgA tTG has high sensitivity and specificity (sensitivity, 95–98%; specificity, 95%) if
on normal (non–gluten-free) diet for at least 4 weeks.

IgA-deficient patients have false-negative IgA anti-tTG antibodies.
IgA deficiency is 10 to 15 times more prevalent in patients with celiac disease.
The tTG antibody test is the preferred test (over the deamidated gliadin peptide [DGP]
antibody).
Follow-Up Tests & Special Considerations
If patient is IgA deficient OR if IgA anti-tTG are negative, follow up with anti-DGP IgA and
IgG.
– Sensitivity, 94%; specificity, 99% (~anti-tTG)
Do not use HLA DQ serotyping for initial diagnosis. Consider if discrepant serology–histology
results in patients unable to test on GFD and children with Down syndrome (1)[C].
Consider bone mineral density testing at the time of diagnosis and after 1 year (if
osteopenia/osteoporosis on initial testing) or 2 years (if normal initially and patient still
symptomatic or nonadherent to diet).
Younger age on diagnosis, less severe initial histologic damage, and male gender increase
likelihood for achieving mucosal recovery.

Pediatric Considerations
Test symptomatic pediatric patients with IgA and IgA anti-tTG antibodies.
Periodic monitoring with IgA anti-tTG Ab can assess dietary adherence.
Negative serology cannot rule out CD.
Consider HLA for high-risk children with negative serology.
Limit IgA antiendomysial antibodies to patients with illnesses that increase false-positive tTG
Ab, such as type I diabetes or autoimmune liver disease.

Diagnostic Procedures/Other
Endoscopy with a minimum of four biopsies of distal duodenum and two of duodenal bulb at
time of initial evaluation correctly diagnose 95% of children (1)[C].
Video capsule endoscopy is a promising alternative with a sensitivity and specificity of 80%
and 95%; particularly helpful if antibody screening and clinical picture are consistent with
celiac disease despite nondiagnostic duodenal biopsies
Test Interpretation
Small-bowel biopsy
Villous atrophy, hyperplasia and lengthening of crypts, infiltration of plasma cells, and
intraepithelial lymphocytosis in lamina propria
Villous atrophy also caused by Crohn disease, radiation enteritis, giardia, and other food
intolerances