Table 11

Inestigation and management of diarrhoea

Investigations	Potential results	Clinical management plan
Actions from history, medication and dietary assessment
History findings	Smoking	Lifestyle advice about smoking cessation.
	Anxiety	Consider referral for psychological support.
	Dumping syndrome	See p. 20.
Medication findings	Drug induced: eg, PPIs Laxatives β blockers Metformin	Medications advice.
Dietary findings	Low/high fibre intake, high fizzy drink intake, high use of sorbitol containing chewing gum or sweets, high caffeine intake, high alcohol intake	Dietary advice about healthy fibre and dietary fat intake. Referral to dietitian and ask patient to complete 7-day dietary diary beforehand. Lifestyle advice about smoking cessation and alcohol/caffeine reduction.
First line
Routine and additional blood tests	Abnormal results	Follow treatment for abnormal blood results (p. 2).
	Mg²⁺ low	Follow treatment for abnormal blood results (p. 2).
	Coeliac disease	Refer to coeliac clinic/dietitians/gastroenterology.
Stool sample for microscopy, culture and Clostridium difficile toxin	Stool contains pathogens	Treat as recommended by the microbiologist and local protocols.
Stool sample for faecal elastase	EPI	Management of EPI (p. 26).
OGD and SI aspirate (p. 25) and SI biopsies	SIBO	Management of SIBO (p. 27).
	Coeliac disease	Refer to coeliac clinic/dietitians/gastroenterology.
	Giardiasis	Metronidazole.
	Other GI pathology	Discuss with supervising clinician within 24 hours.
Glucose hydrogen methane breath test	SIBO	Management of SIBO (p. 27).
Carbohydrate challenge	Carbohydrate intolerance/malabsorption	Management of carbohydrate malabsorption (p. 26).
SeHCAT scan	BAM	Management of BAM (p. 25).
Colonoscopy with biopsies (if frail, consider flexible sigmoidoscopy instead of colonoscopy)	Macroscopic colitis	Send stool culture. If mild or moderate, refer urgently to gastroenterology. If severe, this is an emergency. Discuss immediately with a gastroenterologist.
	Microscopic colitis	Refer to gastroenterology.
	Malignancy	Refer urgently to the appropriate MDT requesting an appointment within 2 weeks.
Second line
Gut hormones	Functioning NET	Refer to the appropriate NET team requesting an appointment within 2 weeks.
Third line
If normal investigations/no response to intervention		Refer to gastroenterology.

BAM, bile acid malabsorption; EPI, exocrine pancreatic insufficiency; GI, gastrointestinal; MDT, multidisciplinary team; Mg²⁺, magnesium; NET, neuroendocrine tumour; OGD, upper GI endoscopy (oesophago-gastroduodenoscopy); PPI, proton pump inhibitor; SeHCAT, 23-seleno-25-homotaurocholic acid; SI, small intestine; SIBO, small intestinal bacterial overgrowth.