Overview
Clinical Meaning
Chronic diarrhea (≥ 4 weeks duration) is classified by mechanism: osmotic (unabsorbed solutes draw water into the lumen—lactose intolerance, sorbitol, celiac disease), secretory...
FNP
FNP
Chronic diarrhea (≥ 4 weeks duration) is classified by mechanism: osmotic (unabsorbed solutes draw water into the lumen—lactose intolerance, sorbitol, celiac disease), secretory (active ion secretion exceeds absorption—VIPoma, bile acid malabsorption, microscopic colitis), inflammatory (mucosal damage with blood/pus—IBD, infection, ischemia), and motility-related (altered transit time—IBS, hyperthyroidism, diabetic autonomic neuropathy). The osmotic gap ([290 − 2 × (Na⁺ + K⁺)] in stool) helps differentiate: > 50 = osmotic, < 50 = secretory. A systematic algorithmic approach using stool studies, serologies, and endoscopy narrows the differential.
Unlock full lesson + practice questions
4 more sections with scenarios, priorities, and review drills.
Next study step
Finish the lesson first, then choose a focused activity to apply what you just reviewed.
Continue studying
Sign in to save progress on this lesson.
Unlock the interactive lesson quiz with a plan that includes this FNP pathway. You can still explore topic-filtered questions from the bank hubs below.