Pathophysiology

During normal processes, approximately 9 L (about 2.4 gallons) of fluid traverse the GI tract daily. Of this amount, 2 L represent gastric juice, 1 L is saliva, 1 L is bile, 2 L are pancreatic juice, 1 L is intestinal secretions, and 2 L are ingested. Of these 9 L of fluid presented to the intestine, only about 150 to 200 mL remain in the stool after reabsorptive processes occur.

Any event that leads to a significant increase in the amount of fluid retained in the stool may result in diarrhea. Large-stool diarrhea often signifies small intestinal involvement, whereas small-stool diarrhea usually originates in the colon. Diarrhea may be classified according to pathophysiologic mechanisms, which include osmotic, secretory, inflammatory, and altered motility.

Osmotic diarrhea results from the intake ofunabsorbable but water-soluble solutes in the intestinal lumen leading to water retention. Common causes include lactose intolerance and ingestion of magnesium-containing antacids.

Secretory diarrhea results in an increase in the net movement (secretion) ofions into the intestinal lumen leading to an increase in intraluminal fluid. Medications, hormones, and toxins may be responsible for secretory activity.

Inflammatory (or exudative) diarrhea results from changes to the intestinal mucosa that damage absorption processes and lead to an increase in proteins and other products in the intestinal lumen with fluid retention. The presence of blood or fecal leukocytes in the stool is indicative of an inflammatory process. The diarrhea of inflammatory bowel disease (e.g., ulcerative colitis) is inflammatory in nature.

Increased motility results in decreased contact between ingested food and drink and the intestinal mucosa, leading to reduced reabsorption and increased fluid in the stool. Diarrhea resulting from altered motility is often established after other mechanisms have been excluded. IBS-related diarrhea is due to altered motility.

Although diarrhea can often be attributed to a specific mechanism, some patients develop diarrhea due to overlapping mechanisms. For example, malabsorption syndromes and traveler's diarrhea are associated with both secretory and osmotic diarrhea.

Drug-induced diarrhea can occur by several mechanisms. First, water can be drawn into the intestinal lumen osmotically. Second, the intestinal bacterial ecosystem can be upset leading to the emergence ofinvasive pathologic organisms triggering secret ory and inflammatory processes. Saline laxatives are an example of the first mechanism, and many antibiotics act by the second. A third way is through altered motility as may occur with tegaserod maleate. Other drugs such as procainamide or colchicine produce diarrhea through undetermined mechanisms. Discontinuation of the offending drug may be the only measure needed to ameliorate the diarrhea.

Constipation Prescription

Constipation Prescription

Did you ever think feeling angry and irritable could be a symptom of constipation? A horrible fullness and pressing sharp pains against the bladders can’t help but affect your mood. Sometimes you just want everyone to leave you alone and sleep to escape the pain. It is virtually impossible to be constipated and keep a sunny disposition. Follow the steps in this guide to alleviate constipation and lead a happier healthy life.

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