Gastrointestinal Diarrhea Overview

Gastrointestinal - Diarrhea

• Diarrhea is an increase in stool frequency, volume, or fluid content.
• It can be osmotic or secretory, based on underlying mechanisms.

Osmotic Diarrhea

• Caused by poorly absorbed substances (e.g., lactose, sorbitol) pulling water into the intestines.
• Stool volume is typically less than 1 liter per day.
• Symptoms improve with fasting.
• Can be caused by conditions like celiac disease or bacterial overgrowth (from antibiotics).

Secretory Diarrhea

• Caused by disruptions in electrolyte transport in intestinal cells.
• Excessive water and electrolyte loss occurs.
• Stool volume is usually greater than 1 liter per day.
• Symptoms persist even with fasting.
• Bacteria like E. coli, Vibrio cholerae (cholera toxin), and some viruses can cause it, as well as hormone-producing tumors and certain medications.

Disease Transmission

• Infectious diarrhea (e.g., cholera, rotavirus, E. coli) is spread through contaminated food/water or person-to-person contact.
• Non-infectious diarrhea (caused by medications, dietary factors, or conditions) isn't contagious.

Risk Factors - Infectious Diarrhea

• Poor sanitation and hygiene.
• Contaminated food and water.
• Young children are more susceptible to severe cases.

Constipation

• Characterized by infrequent or difficult bowel movements, hard stools, and straining during bowel movements.
• Primary (functional) constipation involves normal stool passage rate, but defecation difficulty.
• This can be due to slow transit (reduced colonic motility), Irritable Bowel Syndrome (IBS) type C, or pelvic floor dysfunction.
• Secondary constipation is caused by conditions like dietary factors, medications (opioids, anticholinergics, iron supplements, etc) neurological disorders (multiple sclerosis, spinal cord injury), or structural issues (rectal issues, fissures, prolapses).

Pathophysiology of Constipation

• Slow transit constipation involves slow passage of stool through the colon, leading to excessive water absorption and hard, dry stools.
• Opioid-induced constipation involves the activation of opioid receptors in the gut, which reduces peristalsis and increases water absorption, leading to dry, hard stools.

Disease Transmission (Constipation)

• Constipation is not an infectious disease, so it's not transmissible.
• However, certain medications or lifestyle factors can trigger it.

Risk Factors - Constipation

• Low-fiber diet.
• Dehydration
• Lack of exercise
• Certain medications (e.g., opioids, iron supplements).
• Chronic laxative use