Case Study 1
A 32-year old flight attendant was admitted to the Digestive Diseases Research Centre at St Bartholomew’s Hospital, London. She gave a 7-year history of abdominal pain and diarrhoea, which had been diagnosed as irritable bowel syndrome. The abdominal pain was localised to the right iliac fossa; it was intermittent and relieved by defaecation.
On admission, her bowels were open up to ten times daily with watery motions. She had been a paediatric nurse in the past. Apart from minimal right-iliac-fossa tenderness, physical examination was unremarkable. The following investigations were either normal or negative: full blood examination, urea, electrolytes, liver biochemistry, serum vitamin B12, zinc, magnesium, amylase, endomysial antibody, gut-hormone profile, stool culture, barium follow through, abdominal computed tomography, and gastroscopy with duodenal biopsy. Colonoscopy was macroscopically normal, but biopsy specimens revealed melanosis coli. Urinalysis showed no evidence of laxatives. 3-day stool collection showed true diarrhoea, with daily weights of 524g, 764g, and 684g (normal ≤ 200-250g), with a calculated osmotic gap of 78 mmol/kg (normal <50 mmol/kg). Stool sodium was 74 mmol/L and stool potassium 32 mmol/L. During a 24 h fast with intravenous fluid support, stool output decreased to zero, consistent with an osmotic diarrhoea.
On further questioning, the patient admitted to consuming 60 sticks of sugar-free gum daily. Each stick contains 1.25g sorbitol – an osmotic purgative – giving a total load of 75 g daily. When she stopped chewing the gum, bowel frequency reduced to a single motion daily, and repeat 24 h stool collections showed normalised weights, with an osmotic gap of less than 50 mmol/kg. Sorbitol is a polyalcohol sugar found naturally in fruits, as a common sugar substitute in many dietetic foods, and as a drug vehicle. It is poorly absorbed and can produce a clinical effect in a dose as little as 10g.
– Lancet. 1996 Nov;348(9040):1488.
Case Study 2
A 25-year-old otherwise well male presented with a 12-month history of peri-umbilical pain and some altered bowel habit. He consulted his general practitioner who performed a stool sample which was positive for Blastocystis Hominis. He was prescribed a one-week course of metronidazole, however despite a follow-up negative stool culture, his symptoms persisted. He was then referred for a gastroscopy and colonoscopy, both of which were normal. Biopsies taken from the duodenum were normal, thereby ruling out coeliac disease, and random colonic biopsies were also normal.
Due to persistence of the pain, a CT scan of the abdomen was requested. This revealed what was reported to be a small mass in his right kidney. He was subsequently referred to a urologist to follow-up the CT result. The urologist reassured him that there was an anatomical variant of the kidney, rather than a mass, and it was most unlikely that his symptoms were arising from his kidney. The urologist referred the patient to a gastroenterologist for assessment of his gut symptoms.
His history revealed a diet high in fructose, which may be a potential cause of irritable bowel like symptoms. In fact, upon further questioning the patient volunteered that he had noticed a correlation between the severity of his symptoms and his diet, particularly when he consumed large amounts of certain fruits. He was referred for a fructose hydrogen/methane breath test which was strongly positive. As a result of the test he restricted fructose from his diet, under specialist dietetic supervision, and he has had complete resolution of his original symptoms. He has since seen his dietitian for a review in order to be maintained on the least restrictive diet possible.
Dr Adam Testro (MBBS, FRACP, PhD)
Gastroenterologist & Hepatologist
Head of Intestinal Rehabilitation and Transplantation, Austin Health