A process of exclusion and patience

When a patient presents with stomach problems like diarrhoea and bloating, the lack of guidelines available can make the task of diagnosing gluten intolerance a challenging and time-consuming one for GPs.

Gastroenterologist and Head of Colorectal Medicine and Genetics at Royal Melbourne Hospital, Professor Finlay Macrae, advises GPs to test for coeliac disease first, because of long term risks of cancer and bone loss.

Professor Finlay Macrae is lecturing on gluten intolerance in the upcoming free Healthed webcast on [25th October ]. Register here.

In the first consult, he will also ask the patient to go dairy free for three weeks and monitor for improvements.

“The serology for coeliac disease is pretty reliable for diagnosis, and if it’s positive, a confirmation with a biopsy and gastroscopy,” Professor Macrae says.

“I don’t think any of the breath tests for lactose intolerance are reliable enough or need to be done. The proof is in the pudding.”

Should both return negative results, he says inflammatory bowel disease can be excluded with a high level of certainty with normal ESR, CRP and faecal calprotectin levels.

“Other diagnoses to consider are small bacterial overgrowth, bile salt spill over, and microscopic colitis,” Professor Macrae says.

“If all of these are negative and the patient is under 50 years old, then irritable bowel syndrome (IBS) is the likely diagnosis.”

According to Professor Macrae, some IBS patients benefit from a gluten free diet. For them, he recommends the low FODMAP diet, providing the patient with an information sheet of high FODMAP foods to avoid, and advising them to download and use the Monash FODMAP app.

“I also suggest a dietician. Attention to calcium and vitamin D levels is important, and a patient can run into trouble if they exclude meat and become iron deficient,” he says.

If the patient is showing signs of ongoing distress, Professor Macrae says targeting the gut-brain axis with a pharmacological intervention or clinical psychology can be beneficial.

“Amitriptyline at very low doses is still the main treatment we use to modulate the gut-brain axis and improve symptomatology,” he says.

“A patient might be more amenable and more comfortable with a clinical psychological approach to manage what we’d be now addressing as IBS, having ruled out the other possibilities.”

The jury is still out on the causes non-coeliac gluten sensitivity and how to test for it. Professor Macrae is not a fan of clinical microbiome testing, or the expensive tests patients can undertake at boutique labs specialising in the microbiome.

“There are various hypotheses about agents inciting gluten intolerance, such as the amylase trypsin inhibitor which comes from the pancreas, but the cause and the picture of what’s going on are still uncertain,” he says.

“There’s no good evidence faecal microbial transplantation or probiotics are of any use in IBS. Other microbial testing done by less than mainstream diagnostic labs is difficult to interpret.”

Professor Finlay Macrae is lecturing on gluten intolerance in the upcoming free Healthed webcast on [25th October ]. Register here.