Diarrhea

Defined as bowel movements which are excessive in volume, frequency, or liquidity. Frequency & consistency of fecal discharge are variable among individuals. Diarrhea results from an imbalance in absorption & secretion of water & electrolytes. If absorption of water in the small bowel & colon ↓ or secretion ↑ above normal → diarrhea results.

Clinical presentations: Generally: –Dehydration. –Malnutrition. –Wt loss. –Special vitamin deficiency. In young children: high mortality rate is encountered with gastroenteritis.

Causes of diarrhea: – Infections (viral or bacterial). – Motility disorder, e.g. DM / postsurgical. – Drug induced, e.g. laxative abuse.

Pathophysiology  Change in active ion transport by either ↓ Na + absorption or ↑ Cl - secretion.  A change in intestinal motility.  An ↑ in luminal osmolarity.

Types of diarrhea Secretary diarrhea: secretogogues maintain ↑ rates of fluid & electrolytes secretion or ↓ absorption. Osmotic diarrhea: poorly absorbable substances retain intestinal fluids. Exudative diarrhea: diarrhea associated with discharge of mucus, protein, or blood in the gut.

Constipation

Different definitions of constipation have been used in clinical studies → difficulty in characterizing the problem. –< 3 stools / week →♀, < 5 stools / week → ♂, despite high fiber diet. –A period > 3 days without bowel movements.

Constipation results from ↓ intestinal motility → slow movements of feces through large intestine → dry, hard feces in the descending colon that accumulate because of the long time available for absorption of fluid. Constipation is not a disease; it’s a symptom of an underlying disease problem.

Causes of constipation: 1. Low fiber diet. 2. Medical problem: 1. GI obstruction / tumors. 2. DM. 3. Pregnancy. 4. Drug induced, e.g. analgesics. 5. Psychogenic. 6. Functional cause of constipation is irregular bowel habits that have developed through a lifetime of inhibition of the normal defection reflex.