Chronic diarrhea

Suspect IBS

Small bowel: Imaging, biopsy, aspirate

Colonoscopy + biopsy

End

Limited screen for organic disease: hematology, chemistry, CRP, ESR, Fe, folate, B₁₂, TTG-igA, C4, stool for excess fat, calprotectin

Opioid Rx + follow-up

Stool vol, osm, pH; laxative screen; hormonal screen

Titrate Rx to speed of transit

Alb, albumin; BM, bowel movement; Hb, hemoglobin; IBS, irritable bowel syndrome; MCH, mean corpuscular hemoglobin; MCV, mean corpuscular volume; OSM, osmolality; pr, per rectum.

A. Initial management based on accompanying symptoms or features.

B. Evaluation based on findings from a limited age-appropriate screen for organic disease.

Exclude iatrogenic problem: medication, surgery

Blood p.r.

Fatty diarrhea

Pain aggravated before BM, relieved with BM, sense incomplete evacuation

No blood, features of malabsorption

Consider functional diarrhea

Limited screen for organic disease: hematology, chemistry, CRP, ESR, Fe, folate, B₁₂, TTG-igA, C4, stool for excess fat, calprotectin

Dietary exclusion, e.g., lactose, sorbitol

Low Hb, Alb; abnormal MCV, MCH; excess fat in stool

Low serum K⁺ 

Screening tests all normal

Colonoscopy + biopsy

Small bowel: x-ray, biopsy, aspirate; stool 48 h fat

Stool fat >20 g/day: pancreatic function

Stool fat 14-20 g/day: search for small bowel cause

Normal and stool fat <14 g/day

BA sequestrant

Persistent chronic diarrhea

Colonoscopy + biopsy

Small bowel: x-ray, biopsy, aspirate; stool 48 h fat

Stool vol, osm, pH; laxative screen; hormonal screen

Full gut transit

48 h stool bile acid