DSA 4: Diarrhea Flashcards
how is diarrhea (acute or chronic) clinically described?
- 3 or more loose or watery stools/day
- decrease in consistency and increase in frequency of BM of individual
- loss of bicarbonate and potassium
what is considered NON-inflammatory acute diarrhea?
less than 2 weeks duration
- watery, non-bloody
- usually mild/self-limited
- caused by a virus or non-invasive bacteria
- no workup usually required
what is considered inflammatory acute diarrhea?
less than 2 weeks duration
- blood or pus in stool
- fever
- usually cause by invasive or toxin-producing bacteria
- dx requires routine stool bacterial cultures
what is the main cause of acute diarrhea?
viral gastroenteritis
what is the most common/likely cause of non-infectious diarrhea?
medications
- frequently antibiotics, NSAID’s, Mg laxatives
also caused by food sweeteners (sorbitol) -> said twice that gum contains sorbitol
diarrhea that occurs during the period of antibiotic exposure
- most cases not attributable to C. diff (must differentiate from antibiotic assoc COLITIS)
- dose related
- resolves spontaneously after discontinuation of the antibiotic
- no specific labs or tx
antibiotic-associated diarrhea
what is considered chronic diarrhea?
> 4 weeks
what are the 3 most common causes of chronic diarrhea?
- meds
- IBS
- lactase deficiency/lactose intolerance
what symptoms are inconsistent with the most common causes of chronic diarrhea and warrant further workup?
KNOW!
- nocturnal diarrhea
- weight loss
- anemia
- positive results on fecal occult blood test (FOBT)
what is stool osmotic gap? what is the normal value?
the difference between MEASURED osmolality of the stool (serum) and the ESTIMATED stool osmolality
- normal value is less than 50 mOsm/Kg
what are the clues of osmotic diarrhea?
- stool volume decreases with fasting
- increased stool osmotic gap (greater than 50-75 mOsm/Kg)
sx: abdominal distention, bloating, flatulence
- due to increased colonic gas production
what should pt’s be asked if you suspect osmotic diarrhea?
about their intake of dairy products (lactose), fruits and artificial sweeteners (fructose and sorbitol), and alcohol
what are the most common causes of osmotic diarrhea?
- meds (antacids, lactulose, sorbitol)
- disaccharide deficiency/carbohydrate malabsorption (lactose intolerance)
- laxative abuse (Mg!)
- malabsorption syndromes
stool volume does NOT improve with fasting
- NORMAL stool osmotic gap
- increased intestinal secretion
- **high volume watery diarrhea (>1L/day)
- may develop dehydration and electrolyte imbalance
secretory diarrhea
what are the main causes of secretory diarrhea?
- endocrine tumors (ZES, Carcinoid synd, thyroid carcinoma)
- bile salt malabsorption (Crohn ileitis, ileal resection)
- factitious diarrhea (laxative abuse)
- villous adenoma
what is the initial diagnostic workup of chronic diarrhea?
- CBC
- serum electrolytes (to calculate osmotic gap)
- liver enzymes
- albumin
- vit A/D
- TSH
- IgA tissue transglutaminase (tTG) -> tests for celiac dz
what initial workup should be added if you suspect Giardia or E. histolytica?
- fecal antigen
- wet mounts
What initial workup should be added if you suspect Cryptosporidium and cyclospora?
modified acid-fast staining
most pt with chronic persistent diarrhea should undergo colonoscopy with mucosal biopsy to exclude what?
- IBD (Crohn or UC)
- microscopic colitis
- colonic neoplasia
when is an upper endoscopy with small bowel biopsy performed?
- when a small intestinal malabsorptive disorder is suspected (celiac, Whipple dz)
- AIDS pt to document Cryptosoridium, Microsporida and M avum-intracellulare infection
what further studies are added if malabsorption is suspected?
- pancreatic insufficiency (fecal elastase <100mcg/g)
- chronic pancreatitis (calcification on a plain abdominal radiograph)
- breath tests (glucose or laculose) for small bowel bacterial overgrowth
- hydrogen breath test for carbohydrate metabolism
what further studies are added if neuroendocrine tumors suspected?
- vasoactive intestinal peptide (VIPoma)
- calcitonin (medullary thyroid carcinoma)
- gastrin (ZES)
- urinary 5-hydroxyindoleacetic acid (5-HIAA) carcinoid tumor
what medications are common causes of chronic diarrhea?
- cholinesterase inhibitors
- SSRI’s
- Ang-11 receptor blockers
- NSAIDs
- metformin
- allopurinol
common GI dz in clinical practice
- visceral hyperalgesia (increased sensitivity to pain)
- altered colonic and small-intestinal motility
- enhanced visceral sensation (lower pain threshold in response to gut distention)
- increased frequency of pt presenting with psychological disturbance
IBS
what are the alarm symptoms that are incompatible with dx of IBS and warrant investigation for underlying disease? (7)
- acute onset of symptoms (esp if >40-50 years old)
- noctunal diarrhea
- severe constipation
- hematochezia
- weight loss
- fever
- family hx of cancer, IBD, or celiac
female-male ratio 2:1
- abdominal pain (crampy/lower abd) and irregular bowel habits
- abdominal distention
- relief of abd pain with bowel mvmnt
- increased frequency of stools with pain
- loose stools with pain
- mucus in stools
- sense of incomplete evacuation
IBS
chronic > 6 months (but symptoms for a least 3 months before it can considered in differential)
- is a diagnosis of exclusion
what diagnostic criteria should be used for IBS?
Rome IV clinical diagnosis criteria:
- recurrent abdominal pain, at least 1 day/week in the last 3 months, assoc with 2+ of the following:
- related to (either improves or worsens) with defecation
- change in frequency of stool
- change in form (appearance) of stool
what is the tx of IBS?
meds directed towards diarrhea, constipation, and pain
- dietary intolerances: FODMAPS (reducing these may improve symptoms)
- fermentable oligosaccharides
- disaccharides
- monosaccharides
- polyols
diarrhea, bloating, flatulence, abdominal pain after ingestion of milk-containing products
- dx confirmed by hydrogen breath test
lactase deficiency
- lactase is brush border enzyme that hydrolyzes disaccharide lactose into glucose and galactose
what is the tx of lactase deficiency?
goal of tx is patient comfort
- lactase enzyme replacement available OTC
NOTE: pt who restrict or eliminate milk products may have increased risk of osteoporosis -> Ca supplementation is recommended for susceptible pts
what can cause a temporary lactase deficiency?
viral enteritis
what are the most likely protozoans to cause chronic infections?
Giardia, E. histolytica, Cyclospora
what intestinal nematode is most likely to cause chronic infection?
Strongyloidiases stercoralis
what bacteria most likely to cause chronic infection?
C. diff
what pathogens most likely to cause chronic infection in immunocomprimised/AIDS pts?
- viral: CMV, HIV
- bacterial: C. diff, mycobacterium avium complex (MAC)
- protozoal: microsporidia, cryptosoridium, isospora belli, cyclospora
what is the most common cause of Antibiotic-Associated Colitis?
C. diff
- gram positive, spore-forming bacillus
- cytotoxin A and B production (exotoxin mediated)
- nosocomial transmission (higher risk if hospitalized more than 3 days, or receiving multiple/prolonged abx, or if on PPI)
women > men, 50-60’s, idiopathic condition
- chronic, intermittent watery diarrhea
- normal-appearing mucosa at endoscopy
- histo evaluation reveals chronic inflammation
lymphocytic colitis and collagenous colitis (2 kinds, very similar)
tx: antidiarrheal therapy: loperamide is first-line
- stop offending agent (diarrhea usually abates within 30 days of stopping med)
what medications have been implicated as etiologic agents of colitis?
- NSAIDs
- PPIs
- low-dose aspirin
- selective serotonin re-uptake inhibitors
- ACE inhibitors
- beta-blockers
disruption of digestion and nutrient absorption
- weight loss
- osmotic diarrhea
- steatorrhea (fecal fat >10g/24hr)
- nutritional deficiency
malabsoprtion syndromes
what are the signs of malabsorption?
- loss of muscle mass or subQ fat
- pallor d/t anemia
- easily bruising d/t VitK def
- hyperkeratosis d/t VitA def
- bone pain d/t osteomalacia (VitD?)
- neurologic signs (peripheral neuropathy, ataxia) d/t VitB12 or VitE def
the following are examples of what kind of malabsorption syndrome?
- celiac sprue
- lactase def
- whipple disease
- small bowel resections (short bowel syndrome, bile salt malabsorption)
small bowel mucosal disorders
the following are examples of what kind of malabsorption syndrome?
- chronic pancreatitis
- cystic fibrosis
- pancreatic carcinoma
pancreatic disease/insufficiency
the following are examples of what kind of malabsorption syndrome?
- lymphoma
- carcinoid
- Tb
- kaposi sarcoma
lymphatic obstruction
immunologic response to storage protein gluten (wheat, rye, barley)
- diffuse damage to the proximal small intestinal mucosa with malabsoprtion of nutrients
- only develops in people with the HLA-DQ2 (95%) or HLA-DQ8 (5%) class II molecules
- weight loss
- chronic diarrhea
- dyspepsia
- flatulence
- abdominal distention
- growth retardation
- fatigue
Celiac disease (aka sprue, celiac sprue, and gluten enteropathy)
what does small intestine of celiac disease look like via endoscopy and histologically?
- smooth appearance on endoscopy (loses it’s lumps/bumps)
- villous atrophy on histo slides (loses normal villi structure)
what does destruction of mucosal enterocytes as well as humoral immune response lead to?
antibodies to gluten, tissue transglutaminase (tTG) and other autoantigens
what are the extraintestinal symptoms found in people with celiac disease?
- fatigue
- depression
- iron deficiency anemia
- osteoporosis
- short stature
- delayed puberty
- amenorrhea
- reduced fertility
- dermatitis herpetiformis (pruritic papulovesicles over the extensor surfaces of the extremities, trunk, scalp and neck)
what is the dx and tx of celiac?
- dx: IgA tissue transflutaminase (IgA tTg)
- also check IgG antibodies to anti-DGP, some ppl already have IgA def
- CBC (for anemia)
- dual-energy Xray densitometry scanning (to screen for osteoporosis)
- tx: lifelong removal of all gluten from the diet!
NOTE: celiac disease may be assoc with other autoimmune disorders
significant steatorrhea d/t malabsorption of triglycerides, resulting in:
- weight loss
- gaseous distention and flatulence
- large, greasy, foul-smelling stools
pancreatic insufficiency
NOTE: micellar function and intestinal absorption are normal, so signs of nutrient or vitamin deficiencies are rare
- protein and carb absorption rarely affected
insufficient intraluminal bile salts
- mild steatorrhea (d/t malabsorption of fatty acids and monoglycerides)
- minimal weight loss
- impaired absorption of fat-soluble vitamins results in bleeding tendencies, osteoporosis, and hypocalcemia
- watery secretory diarrhea
bile salt malabsoprtion
rare multi-system disease
- gram positive bacillus, not acid fast (Tropheryma whipplei)
- fever
- weight loss
- malabsorption
- chronic diarrhea
- hypoalbuminemia and edema
Whipple disease
what is the dx, tx and prognosis of Whipple disease?
- dx: endoscopy with duodenal biopsy, periodic acid schiff (PAS)-positive macrophages with characteristic bacillus
- tx: antibiotic therapy drugs that cross BBB
- disease is FATAL is left untreated
what are examples of antibiotics that cross the BBB?
ceftriaxone, meropenem, trimethoprim-sulfamethoxazole
frequent passage of small volumes of stool, often associated with
- rectal urgency, tenesmus (inclination to empty bowels), or a feeling of incomplete evacuation
- accompanies IBS or proctitis
pseudo-diarrhea
involuntary discharge of rectal contents
- caused by neuromuscular disorders or structural anorectal problems
- diarrhea and urgency, especially if severe, may aggravate or cause incontinence
fecal incontinence
elderly/nursing home patients
- fecal impaction that is readily detectable by rectal examination
- severe constipation -> only contents that get by is liquid
overflow diarrhea
NOTE: prolonged impaction can lead to an ulcer!
- pt on opioids, psychiatric dz, prolonged bed rest, neurogenic disorders of the colon, or spinal cord disorders
- decreased appetite
- nausea and vomiting, abdominal pain
- paradoxical diarrhea -> overflow incontinence
fecal impaction
tx: relieving the impaction with enema or DRE
what are the ONLY three contraindications for a DRE?
- you don’t have a finger
- the patient doesn’t have a rectum
- pt has leukopenia (low WBC, could cause dangerous infection)
chronic use of laxative can lead to what?
melanosis coli (benign hyper-pigmentation of the colon)
