Chronic diarrhea

Question 1

How to generally approach chronic diarrhea (3 categories)

Answer 1

Watery (Secretory, motility, or osmotic)

Fatty (malabsorptive)

Inflammatory

Question 2

medications to consider

Answer 2

• metformin
• colchicine
• laxatives
• digoxin
• PPI
• antibiotics
• acarbose
• Mg containing anatacids

Question 3

stool studies to consider

Answer 3

• FOBT
• fecal calprotectin (indicates infectious/inflammatory)
• fecal pH (<5.3 suggests CHO malabsorption, like lactose)

Question 4

Describe osmolar stool gap with watery diarrhea

Answer 4

Stool osmolar gap = 290- 2(NaStool + Kstool)

Gap >125 = osmotic

• osmotically active substance drawing water into lumen
• lactose intolerance? increase sorbitol (sugar free drinks)?
• laxative abuse/use?

Gap 50-125 nl/mixed
-consider IBS or Celiac disease

Gap >50 secretory

• infection
• endocrinopathy (hyperthyroid, cushing)
• malignancy (pheo, VIPoma, carcinoid)
• s/p ileal resection (bile acid malabsorption)

Question 5

tests to consider when suspecting malabsorption

Answer 5

• fecal fat
• stool O+P
• stool elastase can test for pancreatic insufficiency