Investigations

Coeliac serology - three most widely available serological tests include:

• endomysial antibody (EMA)
  • sensitivity and specificity of 95% or more in patients with overt villous atrophy
• tissue transglutaminase (tTG) antibody
  • have both high sensitivity and high specificity at 98% and 95% respectively
  • simpler, cheaper option
  • currently preferred first line test
• deamidated gliadin peptide (DGP) antibody

Small bowel histology

• duodenal biopsy is the ‘gold standard’
• should be done in all patient suspected of having coeliac disease and all those who merit exclusion of coeliac disease
• demonstrates presence of villous atrophy and increased intraepithelial lymphocytes
• recent European paediatric guidelines have suggested an algorithm with the aim of avoiding biopsy in children with clinical symptoms, very high antibody titres and an appropriate genotype (1,2)

Testing for HLA-DQ2 and HLA-DQ8

• has a high negative predictive value hence the disease is very unlikely to develop in persons who are negative for both HLA-DQ2andHLA-DQ8

Other investigations

• FBC - usually dominated by effects of iron deficiency, such as hypochromia, anisocytosis - despite co-existing folate deficiency; Howell-Jolly bodies indicate splenic atrophy, ferritin, vitamin D, calcium may be reduced
• clotting studies may show prolonged prothrombin time from vitamin K deficiency
• liver function - hypoalbuminaemia in severely ill patients

Imaging:

• barium follow through may show mucosal oedema and thickened jejunal folds
• ultrasound may show splenic atrophy

Note:

• inform people (and their parents or carers, as appropriate) that any testing for coeliac disease is accurate only if the person continues to follow a gluten-containing diet during the diagnostic process (serological tests and biopsy if required) (3)

Reference:

• (1) British Society of Gastroenterology (BSG) 2010. The management of adults with coeliac disease
• (2) Mooney PD, Hadjivassiliou M, Sanders DS. Coeliac disease. BMJ. 2014;348:g1561
• (3) NICE (September 2015). Coeliac disease: recognition, assessment Coeliac disease: recognition, assessment and management.