see also: gastroenterology

• now known as gluten enteropathy
• results from an abnormal immune response to gliadin, a component of dietary gluten, found in wheat, barley, rye and possibly oats.
• this causes villous atrophy of the small bowel mucosa, which in turn leads to malabsorption and a predisposition to gastrointestinal malignancy, particularly carcinoma of the oropharynx and oesophagus, and small bowel lymphoma.
• the disease may present in either children or adults, but it is uncommon in adolescence and its manifestations may disappear at this age.

• largely an inherited disorder of Caucasians
• occurs in 10% of first-degree relatives, 30% of HLA-identical siblings and 70% of monozygotic twins.
• however, approximately 20% of the general population have the same HLA alleles but do not develop coeliac disease.
• overall seroprevalence of coeliac disease is 1.4%, both globally and in Australia ¹⁾
• 1st degree relatives of index case screened for HLA‐DQ2/8/7 and serum anti‐tissue transglutaminase (tTG) IgA and anti‐deamidated gliadin peptide (DGP) IgG:
  • 86% had susceptibility haplotypes
  • 11% of child 1st degree relatives had biopsy‐confirmed disease ²⁾
  • 1.4% of adult 1st degree relatives had biopsy‐confirmed disease

• Patients with coeliac disease typically have the HLA-B8, DR3, DQ2 or DQ8 haplotype
• When gliadin enters the small bowel mucosa, it undergoes enzymatic deamidation by tissue transglutaminase (tTG), an extracellular enzyme found in the connective tissue of the small bowel.
• In susceptible people, the gliadin-tTG complex becomes antigenic, producing a local immune response. This leads to the characteristic villous atrophy of coeliac disease. As part of this immune reaction antibodies to tTG are produced and are recognised as endomysial antibodies.

• The classic presentation of a patient with abdominal distension, steatorrhoea, weight loss, bruising and other obvious features of malabsorption is now uncommon.
• adults tend to present with milder symptoms such as:
  • diarrhoea, flatulence and bloating, or fatigue.
  • isolated iron and/or folate deficiency anaemia
• the clinical features have also changed in children who now may present with:
  • growth or pubertal failure, recurrent abdominal pain, iron and/or folate deficiency or malaise.
  • irritability and poor school performance.
• non-GIT presentations:
  • recurrent mouth ulcers
  • delayed menarche, infertility or repeated miscarriage
    • untreated coeliac disease is reported to have a 8-9x risk of recurrent miscarriages compared with treated patients but requires further study³⁾
  • most adults will have significant osteopenia at presentation.
    • 5% of adults diagnosed with osteoporosis will be found to have underlying coeliac disease as the cause
  • at least 75% of patients with dermatitis herpetiformis will be found to have typical villous atrophy on small bowel biopsy whilst most of the others will have more subtle changes.
• other associations:
  • type 1 diabetes
  • autoimmune thyroid disease
  • IgA deficiency
  • atrophic gastritis
  • peripheral neuropathy
  • primary biliary cirrhosis
  • alopecia areata
  • Down's syndrome
  • hyposplenism
  • muscle weakness due to hypokalaemia
  • cryptogenic neurological illness, in particular epilepsy and ataxia (leading to the term `gluten ataxia')
  • non-Hodgkin's lymphoma in < 1% patients
  • NB. arthritis is a rare association although rheumatoid arthritis has increased prevalence

• requires a high index of suspicion
• NB. trial of gluten-free diet has NO place in diagnosis or Rx - gluten-free diet must be lifelong

• if low index of suspicion but alone, these are not diagnostic
• “coeliac disease serology”
  • deamidated gliadin IgG
    • now used instead of endomysial (EMA) antibodies
  • h-Transglutaminase (h-TTG) IgA recomb Ab
    • now used instead of IgA-TTG
    • false negatives may occur if:
      • patient on a gluten-free diet
      • patient has IgA deficiency - 3-5% of patients with coeliac disease
      • the total serum IgA concentration should therefore also be measured at the same time as antibody tests if this is suspected
• useful in checking dietary compliance

• now taken from distal duodenum rather than jejunum
• essential in all patients
• repeat after 6 months on gluten free diet
• if coeliac disease is a possibility, duodenal biopsies should be taken in patients undergoing endoscopy for unexplained iron deficiency anaemia.

• lifelong gluten-free diet
  • gluten refers to two families of proteins (glutenens and gliadins) found in mature grains such as wheat, barley and rye, and thus in foods such as bread, cakes and pasta
  • gluten is sticky, stretchable, elastic, and can act as a thickening agent
  • gluten-free diets can cause deficiency in iron, folate, thiamine, calcium, vitamin B12, and zinc

• Aust Prescr 2001