From the Guidelines
To differentiate between bile acid diarrhea and bile acid deficiency as causes of diarrhea, focus on clinical presentation, response to therapy, and diagnostic testing, with bile acid diarrhea presenting with watery diarrhea that worsens after meals and responds to bile acid sequestrants, while bile acid deficiency causes steatorrhea, weight loss, and fat-soluble vitamin deficiencies, and improves with bile acid supplementation. The clinical presentation of bile acid diarrhea typically includes watery diarrhea that worsens after meals, particularly fatty foods, and may be accompanied by abdominal pain, bloating, and gas 1. In contrast, bile acid deficiency causes steatorrhea (fatty, foul-smelling stools that float), weight loss, and fat-soluble vitamin deficiencies, and improves with bile acid supplementation such as ursodeoxycholic acid (10-15mg/kg/day) 1. Some key points to consider when differentiating between the two conditions include:
- Response to therapy: improvement with bile acid sequestrants like cholestyramine (4-16g daily), colesevelam (625mg, 1-3 tablets twice daily), or colestipol (2g, 1-2 packets twice daily) suggests bile acid diarrhea, while worsening suggests deficiency 1.
- Diagnostic tests: SeHCAT scan (showing increased bile acid loss in bile acid diarrhea), fecal bile acid measurement (elevated in bile acid diarrhea, decreased in deficiency), or 7α-hydroxy-4-cholesten-3-one (C4) blood test (elevated in bile acid diarrhea) can help confirm the diagnosis 1.
- Underlying pathophysiology: bile acid diarrhea involves excess bile acids reaching the colon causing secretory diarrhea, while deficiency results from inadequate bile acids for proper fat digestion, leading to malabsorption 1. According to the most recent guidelines, the Canadian Association of Gastroenterology clinical practice guideline on the management of bile acid diarrhea 2 provides a comprehensive approach to the assessment and management of bile acid diarrhea, including the use of diagnostic tests and therapeutic trials to differentiate between bile acid diarrhea and bile acid deficiency.
From the Research
Differentiating between Bile Acid Diarrhea and Bile Acid Deficiency
To differentiate between bile acid diarrhea and bile acid deficiency as the cause of diarrhea, several factors and diagnostic methods can be considered:
- Clinical Presentation: Bile acid diarrhea typically presents with increased stool frequency, urgency, and looser stool consistency, as well as symptoms such as abdominal pain and fatigue 3, 4.
- Diagnostic Tests: + The selenium homotaurocholic acid test (SeHCAT scan) is considered the gold standard for diagnosing bile acid diarrhea, but it is not widely available and is expensive 5, 6. + Serum markers such as 7α-hydroxy-4-cholesten-3-one (C4) and fibroblast growth factor 19 (FGF19) are being validated for their utility in clinical practice 5, 6. + Faecal bile acid measurement and urine tests are also being explored as potential diagnostic methods 6, 7.
- Pathophysiology: Bile acid diarrhea results from the dysregulation of the enterohepatic recirculation of bile acids, leading to an overproduction or malabsorption of bile acids in the terminal ileum 5, 7.
- Treatment Response: Patients with bile acid diarrhea typically respond well to bile acid sequestrants, while those with bile acid deficiency may require alternative treatments 5, 4.
Key Considerations
- A thorough diagnostic workup is essential to differentiate between bile acid diarrhea and bile acid deficiency, as the treatment approaches differ significantly 5, 4.
- Delayed diagnosis and treatment of bile acid diarrhea can significantly impact a patient's quality of life and increase the overall cost of diagnosis 7.
- Further research is needed to identify more targeted and effective therapeutic strategies for bile acid diarrhea, as well as to develop more accessible and reliable diagnostic methods 3, 5.