Investigations

1st investigations to order

Test
Result
Test

Iron deficiency anaemia is the most common clinical presentation in adults.

Folate (and rarely vitamin B12) deficiency may lead to a macrocytic anaemia.[54]

Result

low Hb and microcytic hypochromic red cells

Test
Result
Test

Order an IgA-tTG test in any patient with suspected coeliac disease.[41]

Higher titres have increased positive predictive value. Serological testing should be done on a gluten-containing diet.

Result

titre above normal range for laboratory

Test
Result
Test

EMA is a more expensive alternative to IgA-tTG with greater specificity but lower sensitivity.

Perform initially if IgA-tTG is unavailable.

Result

elevated titre

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Result
Test

Order this test initially in any patient with skin lesions suggestive of dermatitis herpetiformis.

Both sensitivity and specificity are high.

Result

granular deposits of IgA at the dermal papillae of lesional and perilesional skin by direct immunofluorescence

Test
Result
Test

Test of choice for individuals with IgA deficiency.

Result

elevated titre

Test
Result
Test

IgG-tTG was previously one of the common serological tests for coeliac disease in individuals with known or suspected IgA deficiency. However, this test has been largely replaced by the newer and more accurate IgG DGP or IgA/IgG DGP (deamidated gliadin peptide).

Result

elevated titre

Test
Result
Test

The endoscopic appearance is not sensitive for diagnosis, and may be normal in up to one third of cases at diagnosis.[75]com.bmj.content.model.Caption@67ee18c0[Figure caption and citation for the preceding image starts]: Scalloping of the duodenal mucosa in a patient with coeliac diseaseFrom the personal collection of DA Leffler; used with permission [Citation ends].com.bmj.content.model.Caption@2956be86[Figure caption and citation for the preceding image starts]: Scalloping of the duodenal mucosa in a patient with coeliac diseaseFrom the personal collection of DA Leffler; used with permission [Citation ends].

Result

atrophy and scalloping of mucosal folds; nodularity and mosaic pattern of mucosa

Test
Result
Test

Small-bowel histology is essential and the gold-standard test to confirm the diagnosis.

Biopsies should be performed while on a gluten-containing diet. Patients with an elevated IgA-tTG level should be referred for duodenal biopsy. Small intestinal biopsies should be obtained regardless of the IgA-tTG result in patients with a high clinical index of suspicion.[45]

Two biopsies of the duodenal bulb and at least four biopsies of the distal duodenum should be submitted for histological analysis.

A single biopsy specimen should be collected with each pass of the forceps, to improve the diagnostic quality of the specimens.[23]

Biopsy results are graded using the Marsh criteria.

Result

presence of intra-epithelial lymphocytes, villous atrophy, and crypt hyperplasia

Investigations to consider

Test
Result
Test

This genetic test is useful to rule out coeliac disease in patients already on a gluten-free diet or in patients with an idiopathic coeliac-like enteropathy.

Result

positive HLA-DQ2 or HLA-DQ8

Test
Result
Test

People with coeliac disease on a gluten-free diet prior to evaluation cannot be differentiated from healthy controls. In these patients, gluten challenge is necessary. In a gluten challenge, the person is placed back on a gluten-containing diet (at least 2 slices of wheat bread daily), and serological tests and small bowel histology assessed after 2 to 8 weeks on the gluten-containing diet.[49]

Result

increase in coeliac serological tests and presence of intra-epithelial lymphocytes, villous atrophy, and crypt hyperplasia on small intestinal biopsy

Test
Result
Test

Video capsule endoscopy enables imaging of the entire small intestine and has good sensitivity for the detection of macroscopical features of coeliac disease. In 3% of cases, villous atrophy is only found in the jejunum, reducing the yield of upper endoscopy and duodenal biopsies for diagnosis.[76]

Capsule endoscopy is, however, typically used to detect complications of coeliac disease, such as ulcerative jejunitis or lymphoma.[77][78]

Video capsule endoscopy is not recommended when a stricture is suspected.

Result

atrophy and scalloping of mucosal folds; nodularity and mosaic pattern of mucosa; sensitive for the detection of villous atrophy

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