Adult Diarrhea: Pathophysiology, Classification, Diagnosis, and Treatment

Vocabulary-style flashcards covering the pathophysiology, classification, diagnostic markers, and treatment protocols for diarrhea in adults.

Adult Diarrhea

Defined as stool weight greater than $200\,g/day$.

Secretory Diarrhea

A mechanism caused by bacterial toxins or hormones (e.g., VIPoma or Cholera) characterized by large volume stools that persist even with fasting.

Osmotic Diarrhea

Diarrhea caused by factors like lactose intolerance, sorbitol in sugar-free gum, Mg antacids, or malabsorption, which stops with fasting.

Inflammatory/Exudative Diarrhea

Diarrhea resulting from mucosal damage (e.g., IBD, infectious colitis, or colon cancer) characterized by blood, mucus, fever, and pain.

Motility Diarrhea

Diarrhea associated with urgency, cramps, and small volumes; common adult triggers include IBS-D, hyperthyroidism, and diabetic neuropathy.

Acute Diarrhea

Diarrhea lasting less than $14$ days, which is $90\%$ infectious (viruses, bacteria, or food poisoning).

Persistent Diarrhea

Diarrhea lasting between $14-28$ days, often caused by post-infectious IBS or Giardia.

Chronic Diarrhea

Diarrhea lasting more than $4$ weeks, with common causes including IBD, IBS, celiac disease, bile acid diarrhea, malignancy, or endocrine issues.

Steatorrhea (Fatty Diarrhea)

Bulky, foul-smelling stools that float; common causes include celiac disease, chronic pancreatitis, and small bowel bacterial overgrowth.

Red Flags in Adult Diarrhea

Specific indicators for serious conditions including age greater than $50$, weight loss, nocturnal diarrhea, blood, anemia, and family history of colon cancer or IBD.

Fecal Calprotectin

A stool test used to screen for inflammation; levels greater than $50-100$ warrant a colonoscopy to rule out IBD.

Colonoscopy + biopsy

The investigation used for chronic diarrhea if the patient is age greater than $50$, has blood in stool, or elevated fecal calprotectin, to rule out IBD, microscopic colitis, or cancer.

OGD + duodenal biopsy

The investigation indicated if malabsorption is suspected, specifically to diagnose celiac disease.

Loperamide

An anti-motility agent dosed at $4\,mg$ initially then $2\,mg$ after each loose stool (max $16\,mg/day$); contraindicated if fever, blood, or suspected bacterial dysentery is present.

Azithromycin

An antibiotic used for severe or bloody diarrhea, dosed at $500\,mg$ OD for $3$ days.

Ciprofloxacin

An antibiotic used for severe or traveler's diarrhea, dosed at $500\,mg$ BD for $3$ days.

Low FODMAP diet

A dietary modification used specifically for the treatment of IBS-D.

Cholestyramine

The specific medication used to treat bile acid diarrhea.

Rifaximin

The medication used to treat Small Bowel Bacterial Overgrowth (SIBO).

Budesonide

The medication used for the treatment of microscopic colitis.

Urgent Referral Criteria

Conditions requiring immediate attention: shock/severe dehydration, bloody diarrhea with fever, age greater than $50$ with new bowel habit change, or unexplained weight loss with chronic diarrhea.