This is common in ileal Crohn’s. Due to the fact that bile salts are not being absorbed in the inflamed terminal ileum.
Can get associated reduced absorption of Vitamins ADEK.
Decreased bile salt absorption can lead to precipitation of cholesterol stones.
Decreased bile salt absorption can lead to steatorrhoea. Steatorrhoea promotes the absorption of oxalate which can cause kidney stones.
Bile salts in the colon precipitate diarrhoea.

Causes

Ileal disease or resection (e.g. Crohn’s disease)
Post-cholecystectomy syndrome
- Continuous bile flow due to loss of gallbladder storage and intermittant release during meals
- Increases the bile acid load entering the ileum
- This may overwhelm the ileal reabsorption capacity, especially if borderline or subclinical ileal dysfunction exists
- Excess bile acids escape reabsorption, reaching the colon
IBS-D
Microscopic colitis
Post-radiation enteritis

SeHCAT

SeHCAT = Selenium Homocholic Acid Taurine
Synthetic bile acid analogue labelled with radioactive selenium-75 (^75Se)
How it works
- Patient ingests capsule with ^75Se-labelled bile acid
- Absorbed in terminal ileum and recycled via enterohepatic circulation
- Gamma camera measures retention at:
  - Day 0 (baseline)
  - Day 7 (delayed retention)
Interpretation of results (Day 7 retention)
- 15% → normal
- 10–15% → borderline
- <10% → abnormal
- <5% → severe bile acid malabsorption
Pathophysiological relevance
- Failure to reabsorb bile acids → entry into colon
  - Causes secretory diarrhoea via stimulation of water/electrolyte secretion and colonic motility
- Seen in ileal dysfunction or bile acid overproduction (e.g. post-cholecystectomy)