DIARRHEA –

1. Introduction

• Diarrhea = increase in frequency + fluidity of stool
• Normal stool: ~200 g/day
• Diarrhea:

o   250 g/day

• 70–95% water
• Frequency: 5–20 times/day
• Severe cases: >1.4 L fluid loss/day
• Main risk: Dehydration → morbidity & mortality

Dysentery

• Low-volume, painful, bloody diarrhea

2. Causes of Diarrhea

Infectious Causes

• Bacteria: Shigella, Salmonella, Vibrio, Campylobacter, Staphylococcus, Escherichia coli
• Viruses: Norovirus, Rotavirus
• Protozoa: Entamoeba histolytica

Non-Infectious Causes

• Contaminated food/water
• Poor hygiene, travel history
• Immunocompromised state
• Drugs:
• Antibiotics
• Magnesium antacids
• NSAIDs
• Prostaglandins
• Diseases:
• IBS
• Hyperthyroidism
• Diabetic neuropathy
• Carcinoid syndrome
• Surgical causes: Reduced gut length

3. WHO Classification

• Acute diarrhea: < 14 days
• Chronic diarrhea: > 14 days

4. Pathophysiology

Diarrhea occurs due to imbalance between absorption & secretion of fluids/electrolytes.

Mechanisms

• ↓ Sodium absorption / ↑ Chloride secretion
• Altered intestinal motility
• ↑ Luminal osmolarity
• ↑ Hydrostatic pressure
• Malabsorption

5. Types of Diarrhea

1. Secretory Diarrhea

• Cause: Toxins, hormones (VIP, serotonin, prostaglandins)
• Features:
• Stool > 500 mL/day
• Continues even during fasting

2. Osmotic Diarrhea

• Cause: Poorly absorbed substances (e.g., lactose intolerance, Mg antacids)
• Features:
• Stops with fasting
• High osmolarity stool

3. Exudative Diarrhea

• Cause: Inflammation (e.g., infections, IBD)
• Features:
• Blood, mucus, pus in stool
• Persistent even during fasting

4. Malabsorption Diarrhea

• Cause: Nutrient absorption defects
• Features:
• Bulky, fatty stool (steatorrhea)
• Improves with fasting

6. Management

A. Non-Pharmacological

• Fluid & electrolyte replacement is key
• ORS (Oral Rehydration Solution) – WHO recommended

Home ORS Formula

• 200 mL boiled & cooled water

·       

• 1 teaspoon sugar

·       

• pinch of salt

Diet Advice

• Bland diet
• Avoid:
• Dairy (initially)
• Solid/heavy foods (first 24 hrs)

B. Pharmacological Management

1. Anti-Motility Drugs

• Reduce intestinal motility → ↑ absorption

Examples:

• Loperamide
• Initial: 4 mg, then 2 mg after each loose stool
• Max: 16 mg/day
• Diphenoxylate
• 5 mg QID (max 20 mg/day)
• Opioids (Tincture opium)
• Risk: Addiction

2. Adsorbents

• Bind toxins & reduce symptoms

Example:

• Kaolin-pectin
• Dose: 30–120 mL after each stool

⚠️ Reduce absorption of other drugs

3. Anti-Secretory Agents

Bismuth Subsalicylate

• Used in traveler’s diarrhea
• Adverse effects:
• Black tongue/stool
• Tinnitus
• Encephalopathy (high dose)

Probiotics

• Restore gut flora

Examples:

• Lactobacillus acidophilus
• Lactobacillus bulgaricus

Dose:

• 2 tablets or 1 sachet 3–4 times/day

Octreotide

• Somatostatin analog
• Used in:
• Carcinoid syndrome
• VIP tumors

Dose: 100–600 mcg/day (SC)

Adverse effects:

• Nausea
• Abdominal pain
• Gallstones

4. Antibacterial Agents

Used in infectious/bloody diarrhea

Examples

• Metronidazole / Tinidazole (amoebiasis)
• Fluoroquinolones:
• Norfloxacin 400 mg
• Ciprofloxacin 500 mg
• Ofloxacin 200 mg

✔ Sometimes used in combination

7. Key Exam Points

• ORS = first-line treatment
• Avoid anti-motility drugs in bloody diarrhea
• Dehydration is the main complication
• Fasting helps differentiate:
• Osmotic (improves)
• Secretory (persists)