Diarrhea Flashcards
What constitutes diarrhea?
> 200 grams or 200 mL per 24 hour period
Malabsorptive diarrhea
Inadequate nutrient absorption
Associated with steatorrhea
Relieved by fasting
Exudative diarrhea
Due to inflammatory disease
Purulent, bloody stools
Continue during fasting
What constitutes a normal bowel movement?
One BM every 3 days to 3 BM every day
What are some history clues to investigate with diarrhea?
- Consistency
- Urgency
- Incontinence
- Nocturnal BM
- Flatuphobia
Diarrhea due to small bowel disease
Watery diarrhea, large volume, less frequent
Abdominal cramping, bloating, gas and weight loss
Evidence of malabsorption, vitamin or nutrient deficiencies
Fever is rare
Rare stool WBCs or occult blood
Diarrhea due to large bowel disease
Inflamed dysfunctional colon/rectum cannot perform this function Frequent, small, regular stools Tenesmus (rectal "dry heaves") Painful BM Fever, bloody, mucoid stools RBCs and WBC on stool smear
Osmotic diarrhea
Small intestine and colon cannot maintain an osmotic gradient against serum
Unabsorbed ions remain in the lumen –> pull water into the lumen of bowel
Maintain intraluminal osmolality = 290 mOsm/kg
What are some things that may cause osmotic diarrhea?
Ingestion of poorly absorbed ions or sugars or sugar alcohols – Mannitol, sorbitol, magnesium, sulfate and phosphate
Monosaccharides but not disaccharides can be absorbed
Disappears with fasting
Osmotic diarrhea
Secretory diarrhea
Many causes –> net secretion of anions (chloride/bicarb) or inhibition of net sodium absorption
Most common cause is infection
Enterotoxins
Endocrine tumors
What constitutes acute, persistent and chronic diarrhea?
Acute: 28 days
What are some causes of acute diarrhea?
Infection -- bacteria, parasites, protozoa, viruses Food allergies Food poisoning Medications Initial presentation of chronic diarrhea
What are some causes of chronic fatty diarrhea?
Malabsorption syndromes Mesenteric ischemia Mucosal diseases (celiac, Whipple's) Short bowel syndrome Small intestinal bacterial overgrowth Maldigestion
What are some causes of inflammatory chronic diarrhea?
Diverticulitis Infectious disease Invasive bacterial/parasitic infections Pseudomembranous colitis IBD Crohn's Ulcerative colitis Neoplasia Lymphoma Radiation colitis
What are some main things you must address during the history in a patient who presents with diarrhea?
Assess volume status (symptomatic, orthostatis, fluid intake) Try to assess constancy Frequency Abdominal Pain Tenesmus Nocturnal waking Blood in stool (never normal) Flatuphobia
What are some medications that may cause diarrhea?
NSAIDs and Olmesartan (anti-htn) – sprue like illness
What are some possible causes if diarrhea presents with a fever?
Invasive bacteria Enteric viruses Cytotoxic organism (C. diff or Entamoeba histolytica) Ischemia IBD
What are some causes if diarrhea begins w/i six hours?
Suggests ingestion of toxin
Staph aureus or Bacillus cereus
What are some of the causes of diarrhea if it began within 8-15 hours?
Suggests infection with Clostridium perfringens
What are some of the possible causes of diarrhea if it began more than 14 hours?
Result of viral or bacterial infection, non-specific
How should you focus your physical exam with a patient who is presenting with diarrhea?
Initially focus on volume status
Check for signs of other systemic disease – DH in Celiac disease or EN in arthritis/IBD
Abdominal tenderness/mass
Rectal exam for (fistula, blood stool)
When do you order a stool sample for pathogens?
When a patient is very ill or has risk factors for infection
When do you use ELISAs or DFA microscopy on stool samples?
To test for Giardiasis and Cryptosporidium
-Sensitivities greater than 90%
-Specificities approaching 100%
Useful if proper history or immune compromised
What is the osmotic gap?
Osmotic gap = Serum Osm - Est Stool Osm (290)
The osmolality of colonic fluid contents is in equilibrium with body fluids (290 mOsm/kg)
What is the osmotic gap like in secretory vs osmotic diarrhea?
In secretory diarrhea – the osmotic gap is small (100 mOsm/kg)
What does it mean if the osmotic gap is negative?
There is a poorly absorbed multivalent anion, such as phosphate or sulfate
The measured stool osmolality is of little value – stool osmolality tends to rise once the stool has been collected b/c of continuing bacterial fermentation in vitro.
How can you test for surreptitious laxative ingestion?
There will be a large osmotic gap – suggesting magnesium ingestion
Or a negative osmotic gap
Stool can be analyzed for laxatives by chemical or chromatographic methods
What are some common causes of chronic diarrhea that should be pursued early?
Celiac disease (caucasians)
Thyroid disease
IBD
IBS
When is it appropriate to pursue endoscopy for chronic diarrhea?
Persistent and chronic with significant lab abnormalities – obtain biopsies of even normal appearing mucosa is essential
What does a 72 hour stool collection for fecal fat determine?
7-14 grams considered abnormal but not diagnostic
>14 grams considered indicative of fat malabsorption
