IBD vs IBS
How to tell IBD and IBS apart when a board question makes them look alike.
Step 2 CK pairs are in open beta while clinical review finishes. Spot an issue? Tell us.
Objective inflammatory evidence such as elevated fecal calprotectin is the fastest discriminator favoring IBD.
Side by side
Inflammatory bowel disease is suggested by chronic diarrhea with blood, weight loss, elevated inflammatory markers, or fecal calprotectin elevation.
Irritable bowel syndrome is suggested by recurrent abdominal pain related to defecation with normal basic labs and no alarm features.
IBD causes immune-mediated mucosal inflammation with structural bowel injury.
IBS reflects gut-brain interaction and motility sensitivity without destructive inflammation.
IBD workup may show CRP elevation, anemia, hypoalbuminemia, fecal calprotectin above about 150 mcg/g, and endoscopic ulcers with histologic inflammation.
IBS typically has normal CBC, CRP, and fecal calprotectin, with diagnosis based on Rome symptom pattern after excluding alarm features.
The trap
The trap is labeling chronic abdominal pain and diarrhea as functional before checking for inflammatory red flags. The resolving clue is blood in stool, weight loss, nocturnal symptoms, or abnormal inflammatory markers.
The repair move
Next best step: screen for alarm features and inflammatory markers first. If fecal calprotectin or CRP is elevated or bleeding is present, proceed to colonoscopy with biopsy for IBD classification; if markers are normal and alarm features absent, manage as IBS with dietary and symptom-targeted therapy.
Try a free question
CoreA patient with chronic diarrhea has blood in stool, elevated CRP, and fecal calprotectin 380 mcg/g. What is the next best step in management?
Show answer and explanation
Answer: A. Refer for colonoscopy with biopsy. Inflammatory features require endoscopic evaluation for IBD rather than functional labeling.
Why the other choices are tempting
- B. IBS is unlikely with objective inflammatory abnormalities.
- C. Symptomatic suppression alone delays diagnosis and targeted therapy.
- D. Young age does not exclude clinically significant IBD.
- E. Lactose intolerance does not explain inflammatory markers and bleeding.
Flashcards
Tap a card to flip it.
Which stool marker quickly supports IBD over IBS?
Elevated fecal calprotectin.
What symptom pattern commonly supports IBS?
Recurrent abdominal pain related to defecation without bleeding or systemic inflammatory signs.
Quick answers
What is the fastest way to tell IBD from IBS?
Objective inflammatory evidence such as elevated fecal calprotectin is the fastest discriminator favoring IBD.
What is the key clue for IBD?
Inflammatory bowel disease is suggested by chronic diarrhea with blood, weight loss, elevated inflammatory markers, or fecal calprotectin elevation.
What is the key clue for IBS?
Irritable bowel syndrome is suggested by recurrent abdominal pain related to defecation with normal basic labs and no alarm features.
What is the common trap with IBD vs IBS?
The trap is labeling chronic abdominal pain and diarrhea as functional before checking for inflammatory red flags. The resolving clue is blood in stool, weight loss, nocturnal symptoms, or abnormal inflammatory markers.