Editing Coeliac disease


Gluten-sensitive enteropathy

== Pathogenesis: ==

* Autoimmune disorder triggered by gluten in genetically-predisposed individuals

== Clinical manifestations ==

* Classic symptoms related to malabsorption:
** Diarrhoea
** Steatorrhoea
** Weight loss
** Nutrient or vitamin deficiencies
* Majority have only minor GIT complaints
* Associated conditions:
** Dermatitis herpetiformis (grouped intensely pruritic papules and vesicles, mostly on elbows, dorsal forearms, knees, scalp, back and buttocks)
***
** Atrophic glossitis
** Metabolic bone disease
** Iron deficiency anaemia (UTD says coeliac disease is found in up to 10% of patients presenting for investigation of IDA)
** Selective IgA deficiency
** Other conditions with autoimmune components
** Increased risk for lymphoma and GIT cancer (unclear if the incidence of cancer is affected by good management of coeliac disease)

== Risk factors: ==

* First and second degree relative with confirmed coeliac disease
* T1DM
* Autoimmune thyroiditis
* Down and Turner syndromes
* Pulmonary haemosiderosis

== Investigation: ==

* Serologic tests
** Tissue transglutaminase-IgA is the single preferred test
** Serum tissue transglutaminase IgA and endomysial IgA have similar sensitivities
** Sensitivity depends on severity of disease
** Tests may become negative within weeks of adherence to gluten-free diet
** Positive serology generally mandates a small bowel biopsy to confirm diagnosis
** Serologic tests can give a false negative in: IgA deficiency, gluten-free diet, and mild disease
* Gastroscopy with small bowel biopsy
** Look for: 
*** Atrophic appearing mucosa with loss of folds
*** Visible fissures
*** Nodularity
*** Scalloping
*** Prominent submucosal vascularity
***
*** However, endoscopic visual features alone have a low sensitivity (60-90%)
*** Features can also be seen with giardiasis, autoimmune enteropathy, and HIV infection
** Biopsy:
*** At least four biopsies of post-bulbar duodenum
*** Some advocate for bulb biopsies too, but these are probably not necessary, and if taken should be sent separately and labelled as such to avoid the false-positive finding of villous atrophy on those samples
*** I don't THINK it makes a difference whether they are on gluten for that part

== Diagnosis ==

* Diagnostic criteria: 
** Duodenal biopsy samples showing increased intraepithelial lymphocytes with crypt hyperplasia or also with villous atrophy, in a patient with positive coeliac serology
* Patients on a gluten-containing diet:
** Low disease probability (absence of symptoms or signs of malabsorption such as chronic diarrhoea/steatorrhoea or weight loss; absence of family history; chinese, japanese or sub-saharan african descent)
*** Serologic testing
**** Negative test for an individual with low risk of coeliac disease has a high negative predictive value and obviates the need for small bowel biopsy
*** If positive, gastroscopy with small bowel biopsy
** High disease probability (clinical presentation highly suggestive for coeliac disease, such as chronic diarrhoea/steatorrhoea with weight loss; both risk factors and consistent symptoms/signs)
*** Both serologic testing and small bowel biopsy
* Patients on a gluten-free diet
** Do serologic testing anyway
** If negative, do HLA-DQ2/DQ8 testing
*** If negative coeliac disease excluding
*** If positive, give them gluten for 8 weeks then repeat serology and small bowel biopsy
* Positive serology and nondiagnostic biopsies:
** False-positive tTg - see UTD
** False-negative biopsy - can have a patchy distribution or initially be confined to duodenal bulb
** Can do further tests like HLA-DQ2/DQ8 genotyping - would refer to gastro, I guess
* Negative serology and abnormal small bowel biopsy
** Genetic testing
** If positive, gluten free diet for 12-24 months and monitor clinical response

[[Category:Gastroenterology]]