Chronic Diarrhoea: Diagnosis and Management

Chronic diarrhoea is a common reason for consultation in general practice and secondary care. Despite its high prevalence, making the correct diagnosis can be challenging. The optimal strategy for evaluating these patients varies.

The updated guidance was published by the British Society of Gastroenterology (BSG) in 2018. The BSG guidelines provide more in-depth guidance around the investigation and management of certain conditions. George E Hiner and Julian RF Walters have recently provided some tips to help direct investigations to make the correct diagnosis. The review article was published in the Clinical Medicine Journal in March Issue.

Recommendations for Diagnosis of Chronic Diarrhoea

• The authors mentioned that thorough history is important to identify any precipitating factors.
• They recommended specialists to focus on the presence of red flag symptoms that include unexplained rectal bleeding, unexplained weight loss or an unexplained change in bowel habit for more than 6 weeks in patients older than 60 years.
• They further recommended taking detailed history concerning the time of onset, surgical and family history that helps physicians to diagnose and treat appropriately.

The authors wrote, "Good history taking is necessary, with different causes to be considered: onset and duration of symptoms, previous treatments, co-existing conditions, travel and drug use may all be relevant."

Screening Recommendations

• Routine blood test
• Testing for C-reactive protein for organic disease
• Thyroid function test
• Serological tests for coeliac disease

They also recommended other screening tests such as coeliac serology and faecal calprotectin, to diagnose common organic causes. They further noted, "Exclusion of inflammatory bowel disease and colorectal neoplasia is important and may require colonoscopy."

They said, "When symptoms are significant enough to impact a patient's quality of life, or where simple pharmacological and lifestyle measures have not helped, further investigations are appropriate."

Common Diseases to Consider

• Coeliac Disease: "Coeliac disease serology with tissue transglutaminase antibodies must be checked as part of the screen of investigations in patients with chronic diarrhoea."
• Bile Acid Diarrhoea (BAD): "The selenium homocholic acid taurine (SeHCAT) test, which measures 7-day retention of the 75Se-labelled bile acid, is recognised as the best investigation for BAD, and is widely available in the UK. Excessive loss of bile acids is graded as severe, moderate or mild when 7-day retention is <5%, 5–10% and 10–15%, respectively, and predicts the response of these patients to treatment with bile acid sequestrants such as colesevelam or colestyramine."
• Microscopic Colitis: "Microscopic colitis has been linked to the use of commonly used medications (such non-steroidal anti-inflammatory drugs, proton pump inhibitors and selective serotonin reuptake inhibitors); stopping these medications may alleviate symptoms. For those that do not respond, controlled-release budesonide is an effective treatment."

Drug-Induced Diarrhoea

They noted, "More than 700 medications implicate diarrhoea as an adverse reaction and, in an ageing population with complex comorbidities, we are likely to encounter drug-induced diarrhoea with increasing frequency". They recommended withdrawing the offending medication, however considering on a risk/benefit basis.

Dietary Aspects

Regarding the dietary aspect, they noted, "Dietetic assessment and advice are helpful. Awareness of high FODMAP (fermentable oligo-, di-, mono-saccharides and polyols) foods, with identification of individual sensitivities, is often beneficial".

They further noted, "Symptoms in functional diarrhoea can be helped by attention to dietary factors such as intolerance of lactose and other FODMAPs".