Celiac disease - Investigations

A 26-year-old woman who is known to have type 1 diabetes mellitus presents with a three-month history of diarrhoea, fatigue and weight loss. She has tried excluding gluten from her diet for the past 4 weeks and feels much better. She requests to be tested so that a diagnosis of coeliac disease is confirmed.
What is the most appropriate next step?
A. Check her HbA1c
B. No need for further investigation as the clinical response is diagnostic
C. Check anti-endomysial antibodies
D. Arrange a jejunal biopsy
E. Ask her to reintroduce gluten for the next 6 weeks before further testing

Answer:
E. Ask her to reintroduce gluten for the next 6 weeks before further testing

Discussion:  Serological tests and jejunal biopsy may be negative if the patient is following a gluten-free diet. The patient should eat some gluten in more than one meal every day for at least 6 weeks before further testing.

Celiac disease: Investigations:
 Coeliac disease is caused by sensitivity to the protein gluten. Repeated exposure leads to villous atrophy which in turn causes malabsorption.

Conditions associated with coeliac disease include :

• dermatitis herpetiformis (a vesicular, pruritic skin eruption) and 
• autoimmune disorders (type 1 diabetes mellitus and autoimmune hepatitis). 

Diagnosis is made by a combination of immunology and jejunal biopsy. Villous atrophy and immunology normally reverses on a gluten-free diet.

NICE issued guidelines on the investigation of coeliac disease in 2009. 
If patients are already taking a gluten-free diet they should be asked, if possible, to reintroduce gluten for at least 6 weeks prior to testing.

Immunology
 tissue transglutaminase (TTG) antibodies (IgA) are first-choice according to NICE
 endomyseal antibody (IgA)
 anti-gliadin antibody (IgA or IgG) tests are not recommended by NICE
 anti-casein antibodies are also found in some patients

Jejunal biopsy
 villous atrophy
 crypt hyperplasia
 increase in intraepithelial lymphocytes
 lamina propria infiltration with lymphocytes

Rectal gluten challenge has been described but is not widely used