Diarrhea Flashcards
What is the “textbook” definition of diarrhea?
Why is this not a good definition?
>200 grams or 200mL per 24 hour period
- Difficult to accurately measure
- Patient has to be eating
- High fiber diet can easily get over 300 gm/d
- Does not factor in consistency or frequency
How does Robbins define…
- Malabsorptive diarrhea:
- Exudative Diarrhea:
- Malabsorptive diarrhea:
- Inadequate nutrient absorption
- Associated with steatorrhea
- Relieved by fasting
- Exudative Diarrhea:
- Due to inflammatory disease
- Purulent, bloody stools
- Continue during fasting
What four phases of nutrient absorption are disturbed in malabsorption?
- Intraluminal digestion: break down of proteins, carbohydrates, and fats
- Terminal digestion: Hydrolysis of carbohydrates adn peptides by disaccharidases and peptidases into the brush border
- **Transepithelial transport: **Defects in transport of nutrients, fluid, and electrolytes across SI epithelium
- Lymphatic transport: Defects in lipid absorption
What are some “practical” definitions of diarrhea and normal bowel movement
- Normal BM: One BM every three days to 3 BMs every day
- Diarrhea:
- More than 3 loose/watery stools per day
- Clear increase in frequency and decrease in consistency over baseline
What history clues do you look for in diarrhea?
- Consistency: Liquid > Loose > Soft > formed
- Urgency
- Incontinence – lose control of full BM (not always diarrhea)
- Nocturnal BMs – BM wakes patient up
- Flatuphobia – Fear of poop/fart combo
How much fluid is excreted in feces per day?
<100mL
Small bowel
- Absorptive function:
- Diarrhea characeristics:
- Symptoms:
- Fever?
- Absorptive function: Absorbs most water, nutrients, minerals, sugars and proteins
- Diarrhea characeristics: Watery diarrhea, large volume, less frequent
- Symptoms: Abdominal cramping, bloating, gas and weight loss (evidence of malabsorption/deficiencies)
- Fever?: Rare (Rare stool WBCs)
Large Bowel
Absorptive function:
Diarrhea characeristics:
Symptoms:
Fever?
- Absorptive function: Storage and some fluid/electrolyte absorption (decreased function with inflamed dysfunctional colon)
- Diarrhea characeristics: Frequent, small, regular or bloody mucoid stools,
- Symptoms: Tenesmus (rectal “dry heaves”), painful BM
- Fever?: Yes (RBCs and WBCs on stool smear)
How is osmotic diarrhea due to an abnormal gradient?
- Neither the SI nor the LI can maintain an osmotic gradient against serum
- Unabsorbed ions that remain in the lumen:
- Osmotically active ions act to pull water into the lumen of the bowel
- Maintain an intraluminal osmolality = 290 mOsm/kg
What types of molecules can lead to osmotic diarrhea?
- Ingestion of poorly absorbed ions or sugars or sugar alcohols
- Mannitol, sorbitol, magnesium, sulfate, phosphate
- Monosaccharides but not disaccharides can be absorbed
- Lactase deficiency is most common (loss of nutrient transporter)
Disaccharide deficiency will _______(induce/prevent) malabsorption
Disaccharide deficiency will prevent malabsorption
How is osmotic diarrhea treated? Why does this work?
- Disappears with fasting or cessation of the offending substance
- Electrolyte absorption is not impaired in osmotic dirrhea
- Electrolyte concentrations in stool water are usually quite low
What are the general causes of secretory diarrhea?
What is the most common specific cause?
Either net secretion or anions or inhibition of net sodium absorption
The most common cause is infection
How do enterotoxins play a role in secretory diarrhea?
- Interact with receptors and modulate intestinal transport
- Block specific absorptive pathways, in addition to stimulating secretion
- Inhibit Na+/H+ exchange in both the small intestine and colon
Define…
- Acute Diarrhea:
- Persistent Diarrhea:
- Chronic Diarrhea:
- Acute Diarrhea: ≤ 14 days
- Persistent Diarrhea: 14-28 days
- Chronic Diarrhea: > 28 days
