COELIAC DISEASE (GLUTENSENSITIVE ENTEROPATHY) Medical Assignment Help

Coeliac disease is a condition in which there is an abnormal jejunal mucosa that improves morphologically when the patient is treated with a gluten-free diet and relapses when gluten is reintroduced. Gluten is contained in the cereals wheat, rye, barley and possibly oats. Dermatitis herpetiformis is a skin disorder that is associated with a gluten-sensitive enteropathy.

INCIDENCE

Coeliac disease is common in Europe, with an incidence in the UK of approximately 1 in 2000. In Ireland, however, this is 1 in 300. It occurs throughout the world but is rare in the Black African.

INHERITANCE

There is an increased incidence of coeliac disease within families but the exact mode of inheritance is unknown; 10-15% of first-degree relatives will have the condition, although it may be asymptomatic. Over 90% of patients have the haplotype HLA-A1, B8, DR3, DR7, DQW2 as compared to 20-30% of the general population. However, the fact that not all patients have this haplotype and that as many as 30% of identical twins are discordant for the condition suggests an additional factor such as a Bcell antigen, immunoglobulin heavy-chain allotype or an environmental factor.

AETIOLOGY

Gluten is a high-molecular-weight, heterogeneous compound that can be fractionated to produce a, {3, ‘Y and w gliadin peptides. a-Gliadin is injurious to the small intestinal mucosa although there is some disagreement about the toxicity of other peptides. The exact mechanism of how the damage is produced is still not understood. There are many immunological abnormalities that revert to normal on treatment. An immunogenetic mechanism may be possible in view of the increased incidence of a particular HLA haplotype. An environmental factor, such as a viral infection, may playa role in view of the amino acid sequence homology between gliadin and adenovirus 12.

Disorders of the small intestine causing malabsorption. acid sequence homology between gliadin and adenovirus 12.

Disorders of the small intestine causing malabsorption. acid sequence homology between gliadin and adenovirus

PATHOLOGY

The mucosa of the proximal small bowel is predominantly affected, the mucosal damage decreasing in severity towards the ileum as the gluten is digested into smaller non-toxic fragments. Under the dissecting microscope there is an absence of villi, making the mucosal surface flat. Histological examination shows that the crypts are elongated, with chronic inflammatory cells in the lamina propria. The lesion is described as subtotal villous atrophy, although true atrophy of the mucosa is not present because the crypt hyperplasia compensates for villous atrophy and the total mucosal thickness is normal. The surface cells become cuboidal. There is an increase in the number of lELs (per 100 epithelial cells) which show an increased expression of the ‘Y/6 TCR, instead of the al{3 receptor, and this appears to be specific to coeliac disease. In the lamina propria there is an increase in lymphocytes and plasma cells.

CLINICAL FEATURES

Coeliac disease can present at any age. In infancy it appears after weaning on to gluten-containing foods. The peak incidence in adults is in the third and fourth decades, with a female preponderance. The symptoms are very variable and often non-specific with tiredness and malaise. Common gastrointestinal symptoms include diarrhoea or steatorrhoea, abdominal discomfort or pain and weight loss.
Mouth ulcers and angular stomatitis are frequent and can be intermittent. Rare complications include tetany, osteomalacia, neurological symptoms such as paraesthesia, muscle weakness or peripheral neuropathy, or gross malnutrition with peripheral oedema. There is an increased incidence of atopy and autoimmune disease, including thyroid disease and insulindependent diabetes. Other associated diseases include inflammatory bowel disease, chronic liver disease and fibrosing allergic alveoli tis. Physical signs are usually few and non-specific and are related to anaemia and malnutrition.

INVESTIGATION

JEJUNAL BIOPSY. The mucosal appearance of a jejunal biopsy specimen is diagnostic and this investigation should always be performed in suspected cases. Other causes of a flat mucosa in adults are rare and are shown. If the biopsy is performed endoscopically, a dye can be injected on to the duodenal mucosa to accentuate the smoothness of the mucosa (positive dye test) before the biopsy is taken.
HAEMATOLOGY. A mild or moderate anaemia is present in 50% of cases. Folate deficiency is almost invariably present in coeliac disease, giving rise in most instances to a high MCV. Vitamin B12 deficiency is rare but iron deficiency due to malabsorption of iron and increased loss of desquamated cells is common. A blood film may therefore show microcytes and macrocytes as well as hypersegmented polymorphonuclear leucocytes and Howell-Jolly bodies (due to splenic atrophy).
ANTIRETICULIN ANTIBODIES and endomysial antibodies (IgA) are found in the serum of the majority of cases.
ABSORPTION TESTS are often abnormal but are seldom performed.
SMALL BOWEL FOLLOW-THROUGH may show dilatation of the small bowel with a change in fold pattern; folds become thicker and in the severer forms total effacement is seen.
OTHER BIOCHEMICAL ABNORMALITIES are seen in the severely ill patient, e.g. hypoalbuminaemia.

Small bowel appearances on dissecting microscopy (OM) and histology. (a) Normal mucosa (OM). (b) Coeliac disease (OM); note flattened mucosa. (c) Normal mucosa histology (xl0). (d) Coeliac disease histology showing subtotal villous atrophy.

Small bowel appearances on dissecting microscopy (OM) and histology. (a) Normal mucosa (OM). (b) Coeliac disease (OM);
note flattened mucosa. (c) Normal mucosa histology (xl0).
(d) Coeliac disease histology showing subtotal villous atrophy.

TREATMENT AND MANAGEMENT

A gluten-free diet usually produces a rapid clinical and orphological improvement. Replacement haematinics are given initially to replace body stores. The usual cause for failure to respond to the diet is poor compliance. A gluten challenge, i.e. reintroduction of gluten with evidence of jejunal morphological change, confirms the daignosis. In the straightforw ard cases this is not necessary, although transient gluten intolerance has been described in early childhood. Many patients do not keep to a strict diet but nevertheless maintain good health. The long-term effects of this low gluten intake are uncertain.

COMPLICATIONS

A few patients do not improve on a strict diet unresponsive ‘coeliac disease’). Often no cause for this is found, but intestinal lymphoma, ulcerative jejunitis or carcinoma are sometimes responsible. The incidence of small intestinal T-cell lymphoma  is increased in coeliac disease. Carcinoma of the small bowel and oesophagus as well as extra-gastrointestinal cancers are also seen.  shows the incidence of malignancy compared to the incidence in other gastrointestinal disorders. Malignancy seems to be unrelated to the duration of the disease but the incidence may be reduced by a gluten-free diet.

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Gastroenterology

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