Diagnosis of Coeliac Disease

Coeliac disease is an immunological intestinal reaction to gluten in cereal causing the cells lining the small, intestine bowel to become damaged and inflamed. This is often found in people who are genetically predisposed to this condition.
Coeliac disease in New Zealand
According to international research, approximately 100,000 people across New Zealand have some form of coeliac disease, with around 30,000 of those likely to be children under the age of 18. However, a large proportion of this population group may be well unaware they have the condition, even if they present with some form of symptoms.   
Guidance for referrers
Laboratory testing has an important role in detecting the presence of coeliac disease in a patient and also providing guidance for referrers on identifying symptoms and course of treatment.
When a patient’s bowel becomes inflamed, the villi, which line the inside of the bowel become flat and less effective in breaking down and absorbing nutrients in food. Once this process occurs, a person may present a range of symptoms or manifestations including deficiencies in vitamins (such as vitamin D, vitamin B12 or folate) and minerals (e.g. iron and calcium).
The patient may present with a combination of fatigue, weakness and lethargy, weight loss, osteoporosis (thin bones), diarrhoea or chronic constipation. Other symptoms for adults can include flatulence and abdominal distension, cramping and bloating, nausea and vomiting.
Awanui Labs’ advice to referrers is patients may present showing a range of symptoms, which could indicate the presence of coeliac disease. However, it is possible they may be showing few or no symptoms at all, and while research shows this is becoming more common, coeliac disease may still be present despite a lack of symptoms.
Therefore, to reduce the risk of under-diagnosis, referrers should consider whether a patient may have coeliac disease if they present with any of these symptoms, no matter how severe. A patient’s medical history should also be considered, along with any family history of the disease, to support early testing and prompt diagnosis.
Diagnostic testing for the possible presence of coeliac disease
For most patients, the common way to detect coeliac disease is with the Tissue Transglutaminase IgA antibody (tTG-IgA) test to determine their levels of this antibody in their blood. This test always should be performed on a full gluten-containing diet.
Laboratory testing for coeliac disease is associated with specific genetic markers known as HLA DQ2 and HLA DQ8. These markers can be evaluated for through a patient’s blood sample. These markers are only needed in specific situations and should be ordered only by a specialist gastroenterologist or paediatrician.
Management of coeliac disease includes adherence to strict dietary requirements and removal of food types which contain gluten, monitoring for symptoms which may indicate coeliac disease, and medical treatment if necessary.
Confirmation through a gastroenterologist is required in many cases with an upper gastrointestinal endoscopy and duodenal biopsy. However, in children less than 16 years old, if certain criteria are met, then the diagnosis can be made without the need for a duodenal biopsy (the “biopsy-free” pathway). This will always require confirmation from a paediatric gastroenterologist. Please see local health pathways for more information.
Occasionally the diagnosis of coeliac disease can be made with a skin biopsy as there is a rash associated with coeliac disease called dermatitis herpetiformis.

Dr Richard Steele Medical Director,
Awanui Labs

Professor Andrew Day, 
Paediatric Gastroenterologist,
Waitaha/Canterbury, TWO; 
Cure Kids Chair of Paediatric Research, University of Otago Christchurch