Coeliac Disease

Coeliac disease is a common and often unrecognised disorder that reportedly occurs in up to one in 100 individuals. Both caucasians and non-caucasians are affected but it is extremely rare in chinese, japanese and Afro-Caribbean people.

Pathogenesis and Genetics:
Coeliac disease results from both cell-mediated and humoral responses to ingested gluten. HLA -DQ2 is found in up to 95 % of patients with coeliac while nearly all the remaining population possess HLA-DQ8.

Clinical manifestations:
The classic presentation in infants ( diarrhoea, steatorrhoea, failure to thrive, weight loss and abdominal distension ) is rarely seen now. In recent times, there has been an increasing awareness of more subtle presentations in adults, including:

• Fatigue resulting from anaemia secondary to iron and/or folate deficiency
• Osteopenic bone disease
• Non-specific gastrointestinal symptoms often mimicking irritable bowel syndrome ( bloating, abdominal pain and bowel irregularity )
• Menstrual abnormalities such as late menarche, early menopause and reduced fertility, still birth, recurrent miscarriage
• In men, abnormalities in sperm motility and morphology can result in infertility.

Associated conditions:

• Hyposplenism
• Autoimmune disease such as type I DM, autoimmune thyroid disease, primary biliary cirrhosis and Sjogren's dyndrome.
• Dermatitis herpetiformis
• Increased risk for lymphomas and gastrointestinal malignancies.

Diagnosis:
A gluten free diet is not only expensive but also often tedious and hence a high price to pay for a person who does not suffer from the condition. So it is important to confirm the diagnosis before labelling an individual as having coeliac disease.

Serological testing: four serological tests are available ( IgA tTG antibody, IgA endomysial antibody, IgA antigliadin antibody and IgG antigliadin antibody ). IgA tTG antibody test a sensitivity greater than 95% and a specificity in the range of 90-96%. Antigliadin test has lower diagnostic accuracy than the IgA tTG antibody and anti endomysial antibody test. However, 2-3 % of individuals with coeliac disease have selective IgA deficiency, and so IgA levels should be measureed at the same time to avoid false negatives.

Gastroscopy and Biopsy: The definitive diagnosis of coeliac disease requires a characteristic appearance on histology and at least three biopsies should be taken from the second and third part of the duodenum as the changes due to coeliac disease may be patchy. Histological finding includes villous atrophy, crypt hyperplasia and increased number of intraepithelial lymphocytes in the lamina propria.
The histological pattern seen in coeliac disease is not unique and can be seen in several other clinical situatins including: Giardiasis, Viral gastroenteritis, intestinal lymphoma, Crohn's disease, eosinophilic gastrenteritis, HIV enteropathy and tropical sprue.

If the diagnosis is still uncertain even after biopsy, it is worthwhile checking HLA DQ2 and DQ8.

Ancillary laboratory tests: once coeliac disease is diagnosed, metabolic consequences should be looked for

• Full blood count
• Liver function test
• Iron, B12 and folate
• Calcium, phosphate and Vitamin D level
• TFT
• Blood sugar level
• Bone mineral density measurement