Coeliac Disease Flashcards
What is coeliac disease?
It is defined as an autoimmune condition characterised by gluten sensitivity, in which exposure to gluten causes inflammation of the jejunum
Describe the pathophysiology of coeliac disease
In coeliac disease, gliadin contained within gluten, is not broken down fully and passes through the gastrointestinal tract
In the jejunum, gliadin binds to HLA DQ2 and/or HLA DQ8 genes, activating T-cells in the intestinal mucosa and triggering the immune system
The immune system produces two auto-antibodies, anti-tissue transglutaminase (anti-TTG) and anti-endomysial (anti-EMA)
These antibodies target the epithelial cells of the jejunum, resulting in chronic inflammation
This leads to villous atrophy and thus malabsorption
What are the seven risk factors of coeliac disease?
Young Age, 8 Months Old - 3 Years Old
Middle Age, 40 – 50 Years Old
Female Gender
Family History
Autoimmune Conditions
Genetic Syndromes
IgA Deficiency
What seven autoimmune conditions are associated with coeliac disease?
Type 1 Diabetes Mellitus
Thyroid Disease
Autoimmune Hepatitis
Primary biliary cirrhosis
Primary sclerosing cholangitis
Dermatitis herpetiformis
Irritable bowel syndrome
What two genetic conditions are associated with coeliac disease?
Down’s Syndrome
Turner’s Syndrome
What pneumonic can be used to remember the conditions associated with coeliac disease?
I Don’t Take Apples, I Take Oranges
IgA deficiency
Down’s syndrome
Turner’s syndrome
Autoimmune hepatitis
IgA nephropathy
Type 1 diabetes mellitus
Other autoimmune conditions
What are the ten clinical features of coeliac disease?
Failure To Thrive
Chronic Diarrhoea
Chronic Fatigue
Abdominal Pain
Abdominal Distension
Anaemia Features
Dermatitis Herpetiformis
Mouth Ulceration
Nausea & Vomiting
Weight Loss
How is anaemia a clinical feature of coeliac disease?
It is secondary to malabsorption
What is dermatitis herpetiformis?
It is an itchy, blistering skin rash that is commonly located on the extensor surfaces - elbows, knees and buttocks
What is the cause of dermatitis herpetiformis?
The deposit of IgA in the skin
What gene allele is most commonly associated with coeliac disease?
HLA DQ2
What four investigations are used to diagnose coeliac disease?
Blood Tests
Blood Culture
Genotyping
Endoscopy + Biopsy
What are the six blood test results indicative of coeliac disease?
Decreased Total IgA Levels
Increased Anti-TGG Levels
Increased Anti-EMA Levels
Decreased RBC Levels
Decreased Ferritin Levels
Decreased Vitamin B12 Levels
Why is it essential to check the total IgA levels in suspected coeliac disease?
This is due to the fact that anti-TTG and anti-EMA antibodies are IgA
Therefore, in cases where individuals have decreased total IgA levels, the antibodies will present negatively – even when they have coeliac disease
In this circumstance, we test for the IgG version of anti-TTG or anti-EMA antibodies or conduct an endoscopy + biopsy
What is the first line investigation for coeliac disease?
Anti-TTG blood test
What anti-TTG level is indicative of coeliac disease?
x 10 of the upper limit
When should anti-EMA levels be conducted?
It should only be performed if anti-TTG levels are unavailable
This is due to the fact that anti-EMA testing is a more expensive alternative to anti-TTG
Why are decreased RBC, ferritin and vitamin B12 levels indicative of coeliac disease?
This is due to anaemia development secondary to malabsorption
What five blood culture results indicate coeliac disease? Why?
Target Cells
Howell-Jolly Bodies
Pappenheimer Bodies
Siderotic Granules
Acanthocytes
These are features of hyposplenism, a complication of coeliac disease
How is genotyping used to diagnose coeliac disease?
It is used to determine the presence of HLA DQ2 and HLA DQ8 genes within the genome
Does genotyping provide a definitive diagnosis of coeliac disease? Why?
No
This is due to the fact that individuals can be HLA DQ2 and HLA DQ8 positive with no coeliac disease
Instead, it is used to exclude coeliac disease
What is the gold standard investigation used to diagnose coeliac disease?
Endoscopy with biopsy
In which section of the small intestine, do we conduct a biopsy in?
Duodenum
When is endoscopy, with biopsy, used to investigate coeliac disease?
When serology markers are positive
