GI: Diarrhea

Profuse, watery diarrhea due to small bowel hypersecretion is due to ingestion of (2).

1. preformed bacterial toxin. 2. enterotoxins.

Traveller's diarrhea in a patient returning from Nepal is most likely caused by ____.

Cyclospora

Stool Consistency

Diarrhea refers to types 5, 6, and 7.

Diarrhea: Osmotic Diarrhea Ill-Appearing: Hydration Status: Stool: Stool Na+: Stool pH: Effect of Food: Stool-Reducing Substance: Perianal Excoriation: Osmotic Gap:

Diarrhea: Osmotic Diarrhea Ill-Appearing: Hydration Status: Stool: Stool Na+: Stool pH: Effect of Food: Stool-Reducing Substance: Perianal Excoriation: Osmotic Gap:

What is the pathophysiology of diarrhea?

Each day, about 8 to 10 L of fluid, a combination of fluid from the salivary glands, stomach, biliary system, and pancreas, enters the jejunum, and the small intestine absorbs about 90% of this fluid load. As a result, about 1.5 L of this fluid load reaches the colon. The colon then absorbs 90% of the fluid load left. About 100 ccs is excreted in the stool. So, any decrease in absorption or an increase in secretion leads to diarrhea. Disruption of epithelial electrolyte transport or its regulatory system by toxins, drugs, hormones, and cytokines is a major cause of diarrhea.

Traveller's diarrhea in a patient returning from Russia is most likely caused by ____.

Giardia

What is the most common cause of chronic secretory diarrhea in the US?

Medications are the most common cause of chronic secretory diarrhea in the US.

What is the most common cause of acute diarrhea?

The most common cause of acute diarrhea is infection.

What is the most common clinical syndrome of disaccharidase deficiency?

The most common clinical syndrome of disaccharidase deficiency is acquired lactase deficiency, which accounts for lactose intolerance in many adults.

What is travelers diarrhea?

Travelers diarrhea is a form of acute diarrhea that results in water diarrhea and mild abdominal pain for 24 hours, but can last up to a week.

Steatorrhea

foul-smelling, greasy diarrhea

When the left colon is infected, patients have _________ bowel movements. Why?

frequent small-volume, painful bowel movements; This is because the sigmoid colon functions in storage. So, when infected, it will be unable to hold stool, leading to frequent bowel movements. Also, when the rectum is affected, pain occurs.

Muscle wasting is a sign of _____.

malnutrition

Viral etiologies of diarrhea present with a ______ CBC.

normal

Traveller's diarrhea in a patient returning from a cruise is most likely caused by ____.

norovirus

Which two DM drugs can cause diarrhea?

1. Acarbose 2. Metformin

In patients with institutionalized or hospitalized patients, (2) should be considered as causes of acute diarrhea.

1. Clostridium difficile toxin-mediated colitis 2. drug side effects

(2) are associated with HUS.

1. E. coli 2. Shigella sp.

What are the two major clinical classifications of diarrhea?

1. Acute Diarrhea (<4 weeks): Acute diarrhea is usually caused by infection, which is generally self-limited or easily treated. The most common bacterial and viral causes of diarrhea run their course within 7 days. 2. Chronic Diarrhea (> 4 weeks): A clinician must consider noninfectious causes.

Additional workups in patients with acute diarrhea include: (6)

1. CBC. 2. serum electrolytes, Cr, and BUN (CMP). 3. stool testing. 4. abdominal imaging. 5. flex sigmoidoscopy or colonoscopy. 6. biopsies.

How is diarrhea treated? (3)

1. Fluid and Electrolyte Replacement 2. Empirical Therapies: Fluoroquinolones or rifaximin can be used for travelers diarrhea or ill patients with febrile dysentery. For patients with persistent diarrhea (lasting > 1 week), an empirical trial of metronidazole for a protozoal infection is sometimes considered. 3. Nonspecific antidiarrheal agents (i.e. Imodium) can reduce stool frequency, stool weight, and coexisting symptoms like abdominal cramps.

A patient presents with diarrhea after eating raw seafood. Consider (3) causes.

1. Hepatitis A 2. Salmonella sp. 3. Vibrio sp.

Symptoms of Ischemic Colitis (3)

1. Lower Abdominal Pain 2. Diarrhea 3. Bloating

Etiologies of diarrhea in AIDS patients include: (8)

1. Mycobacterium species. 2. Cytomegalovirus. 3. Adenovirus. 4. Herpes simplex. 5. Cryptosporidium. 6. Isospora belli. 7. Microsporidia. 8. Blastocysts hominis.

A patient presents with diarrhea after eating mayonnaise and cream puffs. Consider (2) causes.

1. S. aureus 2. Salmonella sp.

(4) are associated with reactive arthritis, urethritis, and conjunctivitis following acute diarrhea.

1. Salmonella 2. Campylobacter 3. Shigella 4. Yersinia

A patient presents with diarrhea after eating chicken. Consider (3) causes.

1. Salmonella sp. 2. Campylobacter jejuni 3. Shigella sp.

Causes of daycare associated diarrhea include: (4)

1. Shigella. 2. Giardia. 3. Cryptosporidium. 4. Rotavirus.

Symptoms of Yersinia (3)

1. Tenderness 2. Abdominal Pain 3. Mimics Acute Appendicitis

What are the five major groups of acute diarrhea?

1. Traveler's Diarrhea 2.

What are the five major groups of acute diarrhea?

1. Traveler's Diarrhea 2. Food-Related Diarrhea 3. Diarrhea in Immunodeficient Patients 4. Daycare Associated Diarrhea 5. Nosocomial Diarrhea

Etiologies of diarrhea in hemochromatosis patients include: (2)

1. Vibrio sp. 2. Yersinia sp.

Symptoms of Acute Diarrhea (3)

1. Vomiting 2. Fever 3. Abdominal Pain

In patients with DM, (3) should be considered as causes of acute diarrhea.

1. altered motility. This can lead to bacterial overgrowth. 2. associated diseases (i.e. celiac disease and pancreatic insufficiency) 3. drug side effects

Risk factors for nosocomial diarrhea include (3):

1. antibiotic therapy. 2. hospitalization. 3. immunosuppression (i.e. patients with IBS on biologics).

Yersinia is associated with (3) following acute diarrhea.

1. autoimmune-type thyroiditis. 2. pericarditis. 3. glomerulonephritis.

The treatment for travelers diarrhea is (2).

1. azithromycin. 2. fluoroquinolones.

In travelers, (3) should be considered as causes of acute diarrhea.

1. bacterial infection 2. protozoal infections (i.e., amebiasis, giardiasis) 3. tropical sprue

In epidemics and outbreaks, (3) should be considered as causes of acute diarrhea.

1. bacterial infections 2. protozoal infection (cryptosporidiosis) 3. viral infection (i.e.., rotavirus)

Travelers diarrhea prophylaxis includes (2).

1. bismuth. 2. rifaximin.

In patients with AIDS, (3) should be considered as causes of acute diarrhea.

1. drug side effects 2. lymphoma 3. opportunistic infections (i.e., cryptosporidiosis, cytomegalovirus, HSV, Mycobacterium avium complex)

Traveler's diarrhea is most commonly due to: (8)

1. enterotoxigenic or enteroaggregative E. coli. 2. Campylobacter sp. 3. Shigella sp. 4. Aeromonas sp. 5. Norovirus 6. Salmonella sp. 7. Giardia. 8. Cyclospora.

Cytotoxins and invasive microorganisms present with (3).

1. fever. 2. abdominal pain. 3. bloody diarrhea.

Causes of osmotic diarrhea include (2):

1. ingestion or a poorly absorbed agent (i.e. Mg+ ingestion). 2. reduced nutrient transport (i.e. lactase deficiency).

Diarrhea associated with preformed bacterial toxins or enterotoxins presents with: (4)

1. marked vomiting. 2. minimal or no fever. 3. abdominal cramping. 4. bloating.

Causes of secretory diarrhea include: (6)

1. medications. 2. enterotoxins (exogenous secretagogues). Enterotoxins originate from bacteria and viruses. Enterotoxins interrupt receptors that modulate intestinal transport, leading to increase anion secretion. 3. peptides produced by endocrine tumors (i.e. VIPoma) (endogenous secretagogues). 4. absence of ion transporters (i.e. congenital chloridorrhea). 5. loss of intestinal surface area (i.e. intestinal resection or diffuse intestinal mucosal disease like Crohn's or celiac disease). 6. rapid intestinal transit (i.e. intestinal hurry following a vagotomy).

Other causes of acute diarrhea include (5):

1. medications. 2. ischemic colitis. 3. diverticulitis. 4. toxins. 5. initial presentation of chronic

Signs of dehydration include: (3)

1. orthostasis. 2. hypotension 3. muscle wasting.

Indications for further evaluation (i.e. stool tests or admission) of acute diarrhea include: (6)

1. profuse diarrhea with dehydration. 2. bloody diarrhea. 3. fever duration > 48 h without improvement. 4. severe abdominal pain in patients 50+ years (think ischemic colitis). 5. immunocompromised. 6. recent use of antibiotics (think C. diff.).

Watery diarrhea implies (2).

1. secretory diarrhea. 2. osmotic diarrhea.

Diarrhea must be differentiated from (2).

1. tenesmus. 2. fecal incontinence.

Ischemic colitis is seen in patients _____.

50+

A patient presents with diarrhea after eating fried rice. Consider (1) cause.

B. cereus

What is the most common cause of nosocomial diarrhea?

C. diff. is the most common cause of nosocomial diarrhea.

What is diarrhea?

Diarrhea is a condition due to an excess of stool water resulting from abnormal water and electrolyte transport. It is defined as > 200 g of stool per day or three or more loose or liquid stools in 24 hours.

Diarrhea: Secretory Diarrhea Ill-Appearing: Hydration Status: Stool: Stool Na+: Stool pH: Effect of Food: Stool-Reducing Substance: Perianal Excoriation: Osmotic Gap:

Diarrhea: Secretory Diarrhea Ill-Appearing: Hydration Status: i.e. hypokalemia Stool: Stool Na+: Stool pH: Effect of Food: Stool-Reducing Substance: Perianal Excoriation: Osmotic Gap:

Traveller's diarrhea in a patient returning from camping and backpacking is most likely caused by ____.

Giardia

A patient presents with diarrhea after eating unpasteurized milk. Consider (1) cause.

Listeria sp.

What is osmotic diarrhea?

Osmotic diarrhea is a form of diarrhea caused by the ingestion of poorly absorbed sugars, sugar alcohols, cations, and anions. So, for example, when disaccharides like sucrose and lactose are ingested, the absence of the appropriate disaccharidase will preclude absorption of the disaccharide or its component monosaccharides.

How is osmotic diarrhea treated?

Osmotic diarrhea usually resolves with fasting or cessation of ingestion of the offending substance. For example, in the case of lactose intolerance, osmotic diarrhea ceases when the patient stops ingesting dairy.

A patient presents with diarrhea after eating eggs. Consider (1) cause.

Salmonella sp.

What is secretory diarrhea?

Secretory diarrhea is a form of diarrhea in which there is a net secretion of anions, such as Cl- or bicarbonate, or K+ or net inhibition of Na+ absorption.

Why is surgery an important historical factor to diarrhea?

Surgery is an important historical factor to diarrhea because small bowel resection can lead to diarrhea.

What is the mechanism of action of E. coli heat stable toxin?

The E. coli heat stable toxin interacts with the GC-C receptor on the luminal surface of the enterocyte. This causes inhibition of reabsorption and of the Na+/K+ ATPase in the intestines.

The activity of lactase __________ with age.

decreases

Fatty diarrhea implies ______.

defective absorption of fat

A patient presents with diarrhea after eating hamburger. Consider (1) cause.

enterohemorrhagic E. coli (O157:H7)

Suspected steatorrhea can be confirmed with a _______.

fecal fat test

Acute diarrhea is spread via ______.

fecal-oral transmission

In osmotic diarrhea, electrolyte absorption (is/is not) impaired in osmotic diarrhea, and electrolyte concentrations in stool water are usually (low/high).

is not; low

Abdominal imaging rules out ______ in the presence of abdominal pain and diarrhea.

ischemic colitis

When infections infect the small bowel, the patient has ________ bowel movements.

large

When the right colon or small bowel is infected, patients have _________ bowel movements. Why?

less frequent, larger, and painless; This is because secretions are affected.

Bacterial etiologies of diarrhea present with ________ on CBC.

leukocytosis

Salmonella that causes diarrhea presents with ______ on CBC.

neutropenia

Patients with hemochromatosis should avoid _______.

raw fish

Physical exam determines the ______ of diarrhea.

severity

When infections infect the large bowel, the patient has ________ bowel movements.

small, more frequent

Yersinia invades the (2)

terminal ileum and proximal colon mucosa.

Inflammatory diarrhea implies ________

the presence of one of a limited number of inflammatory or neoplastic diseases involving the GI tract

IBS typically begins following ______.

viral or bacterial gastroenteritis