Disorders of Small Intestine / Colon Flashcards
Malabsorptive Disorders of the Small Intestine
Celiac Disease
Whipple Disease
Bacterial Overgrowth
Short Bowel Syndrome
Lactose Intolerance
Normal digestion is broken down into 3 phases
-
Intraluminal: dietary fats, proteins, carbs are hydrolyzed and solubilized by pancreatic and biliary secretions
- Fats are broken down by pancreatic lipase to monoglycerides and fatty acids that form micelles with bile salts
- Micelles are important for solubilization and absorption of fat-soluble vitamins (A, D, E, K)
- Proteins are hydrolyzed by pancreatic proteases to di and tripeptides and amino acids -
Mucosal: requires sufficient surface area of intact small intestinal epithelium
- Brush border enzymesare important in the hydrolysis of disaccharides and di-and tripeptides
- Malabsorption of specific nutrients may occur as a result of a deficiency in an isolated brush border enzyme -
Absorptive
- Impaired absorption of chylomicrons and lipoproteins may lead to steatorrhea and significant enteric protein losses
which malabsorptive disorder has an abnormal response to gluten/gliadin?
Celiac Disease
Permanent dietary disorder caused by an immunologic response to gluten, which is a storage protein found in certain grains
Results in diffuse damage to the proximal small intestinal mucosa with malabsorption of nutrients
celiac dz is MC in who?
- M/C - Caucasians
- Genetic predisposition
- First and second degree relatives are at higher risk
pathophys of celiac dz
- Dietary gluten triggers immune response that damages proximal small
Intestine mucosa and cause villous atrophy - Results in malabsorption of nutrients
- Wheat-containing foods, cause gluten and gliadin build up in intestinal mucosa, causing direct damage
- Also causing humoral immune and slight T-Cell mediated response causing antibody
production
classic presentation of celiac dz
- Diarrhea, Steatorrhea, Flatulence - Bulky, foul-smelling, floating
- Dyspepsia
- Weight loss
- Abdominal distention
- Weakness, Muscle Wasting
- Growth Retardation in Children
- Resolution of sx upon Gluten-containing food withdrawal
atypical presentation of celiac dz
Fatigue, Depression
Iron-Deficiency Anemia, Vitamin B12 or Folate deficiency
Osteoporosis, bone pain
Amenorrhea, Infertility
Easy Bruising
Peripheral neuropathy, Ataxia
Dermatitis herpetiformis
Delayed puberty
Increased risk for gastric cancer
Pruritic papulovesicular rash - itchy
Extensor surfaces of extremities and trunk, scalp, and neck
Most pt have Celiac Disease
what are these lesions
Dermatitis Herpetiformis
diagnostic work-up for celiac disease
- IgA TTG antibody tests - 98% sens/specificity
- Total IgA levels
- IgA anti-endomysial antibody and IgG DGP (deamidated gliadin peptides)
gliadin - protein found in wheat gluten - Levels become undetectable after 6-12 months of gluten free diet
- Used to monitor progress/compliance - any vitamin/nutrient deficiencies
Pt continues to eat normally before testing
what enzyme is released by inflammatory cells that change the chemical structure of gliadin, making gliadin more immunogenic
tissue transglutaminase (TTG)
IgA TTG falsely negative in patients with ?
IgA deficiency
hence why get total IgA levels for celiac dz
imaging for celiac dz
-
Endoscopic mucosal bx of proximal and distal duodenum - dx
- mucosal bx for negative serum but have sx too - Atrophy of duodenal folds shown on endoscopy
- Or nodular, scalloping of duodenal folds, fissuring, & mosaic patterns of duodenal mucosa
Histology in endoscopic mucosal bx shows intraepithelial lymphocytosis
Blunting or a complete loss of intestinal villi
what is this dx
celiac dz
management for celiac dz
- avoid gluten 4eva - wheat, rye, barley
- Improvement w/n 1-2 wks
- Dietary supplements if vitamin deficient
cause of whipple dz
Tropheryma whipplei - G+, non-acid fast, PAS positive bacillus; ubiquitous in environment
Rare malabsorptive infectious disease
- fecal-oral tramission
- easily spreads throughout body = evades immune response
- immunodeficiency is predisposing factor (hypothesis)
presentation of whipple disease
- Continually changing sx
- MC sx:
- Arthralgias - 1st sx noted
- Diarrhea, abd pain
- wt loss (MC) - other GI: malabsorption, gas, steatorrhea
- neurological possible: dementia, lethargy, coma, seizures
- PE: Low-grade F, malabsorption signs, enlarged joints, LAN
work-up + result for whipple dz
- DX: upper endoscopy w/ bx of duodenum - Macrophages w/ G+ bacilli (PAS positive macrophages) (pathognomonic)
- Confirm: PCR - done only if endoscopy is inconclusive
tx for whipple dz
- IV Ceftriaxone x 2-4 wks
- allergic: IV Meropenem x 2-4 weeks - Then TMP-SMX BID x 1 yr
A condition in which colonic bacteria are seen in excess in the small intestines; when present, intestinal symptoms can arise
Small Intestine Bacterial Overgrowth
Stomach and proximal short bowel contains only a small amount of bacteria d/t ?
gastric acidity and effects of peristalsis
An intact ileocecal valve helps prevent retrograde translocation of bacteria
causes of Small Intestine Bacterial Overgrowth
- Motility disorders
- Anatomic disorders (adhesions from prior surgeries)
- Other metabolic disorders (DM)
- Immune disorders
sx of Small Intestine Bacterial Overgrowth (SIBO)
- Some asx until vitamin def
- bloating, flatulence, diarrhea/steatorrhea, wt loss, acne, rashes
SIBO suspected with aforementioned sx and a hx of GI surgery or predisposed
work-up for SIBO
- confirm: small intestine aspiration w/ cx - invasive tho
- carbohydrate breath test - administration of lactulose = early peak in breath hydrogen lvls
how does a carbohydrate breath test work for SIBO?
metabolism of a test dose of carbohydrate substrate (lactulose, glucose) by bacterial flora leads to production of hydrogen, which is absorbed and ultimately excreted in the breath
how to prep for a carbohydrate breath test?
one day before test:
- Stop using all meds related to your GI tract (acid suppression, abd pain/spasm, D/C)
- NO carbs in following categories: bread, pasta, potatoes, rice, crackers, oatmeal, cereals, or any other starchy food products.
tx for SIBO
- When possible, anatomic defect corrected
- 7-10 d abx
- Ciprofloxacin 500mg BID preferred
- Augmentin
- TMP-SMX
cause of short bowel syndrome
- Secondary to removal of portion of small intestine
- d/t Crohn’s dz, ischemia, tumor, trauma, mesenteric infarction, volvulus
sx of short bowel syndrome
Vary depending on amount and section of intestine removed
- Terminal ileal resection = malabsorption of B-12 and bile salts
- Extensive bowel resection
- >50% of total length of small intestine
- wt loss and diarrhea d/t nutrient malabsorption
management for acute phase of short bowel syndrome
Initial 3-4 wks after resection
- Stabilize large fluid/lyte losses
- Acid suppression - IV PPI
- Parenteral nutrition, graduating to enteral feeding
Management of Adaptation phase in short bowel syndrome
- Transition to oral feedings in slow and stepwise manner over a period of wks-months
- Complex carbohydrates
- Low fat
- Fluid management
- PPIs
- Antidiarrheals prn
- abx for SIBO
a brush border enzyme that hydrolyzes the disaccharide lactose into glucose and galactose
lactase
cause of lactase deficiency
deficiency of lactase
- lactase steadily declines with age
- MC non-European descendants
presentation of lactose intolerance
diarrhea, bloating, flatulence, and abdominal pain after ingestion of dairy products
work-up for lactose intolerance
- DX: hydrogen breath test
- After ingestion of 50g of lactose, a rise in breath hydrogen within 90 min is a positive test
Pt should be fasting for 8 hrs prior to test
tx for lactose intolerance
- Lactose free diet/Lactose minimizing diet
- Lactase supplementation - Lactaid
A condition in which there is neurogenic failure or loss of peristalsis in the intestine in the absence of any mechanical obstruction
what is this dx
Paralytic Ileus
Paralytic Ileus is MC in who?
in hospitalized pts as a result of:
- Intra-abdominal processes such as recent GI or abdominal surgery
- Peritoneal irritation (pancreatitis, hemorrhage)
- Severe medical illness (pneumonia, sepsis, respiratory failure)
- Meds that affect intestinal motility (opiods, anticholinergics)
Following surgery, which part of the digestive system usually normalizes first in motility?
followed by what part? (after 24-48 hours)
then what? (48-72 hours)
small intestinal motility first
stomach
colon
There is a “normal” period of time, lasting <4 d: from surgery until passage of flatus or stool and tolerance of an oral diet
cause/pathophys of paralytic ileus
- After abd surgery, it results from inflammatory response to intestinal manipulation and trauma
- activates local macrophages = muscle dysfunction - Inhibitory neural reflexes act locally through noxious spinal afferent signals that increase inhibitory sympathetic activity = Slowing motility
- Opioids inhibit GI tract motility = Increase resting tone while decreasing motility and emptying
presentation of paralytic ileus
N/V/obstipation, abdominal discomfort
Abdominal distention with tympany to percussion
Diminished/Absent bowel sounds
Diffuse abdominal pain
work-up for paralytic ileus
Can be clinical diagnosis if last >4 d
-
Plain films - Distended/dilated gas-filled loops of bowel
- Air in colon and rectum as well - CT - if can’t distinguish ileus vs SBO
- labs:
- CBC: r/o infection, ischemia, or abscess
- CMP: hypokalemia can worsen ileus
- BUN/Creatinine: uremia can lead to ileus
- LFTs, Amylase, Lipase: gallbladder dysfunction or pancreatitis can lead to ileus
tx for paralytic ileus
- Underlying cause
- Complete Bowel rest
- IV fluids/TPN
- NG tube - Slowly advance diet
- Activity
- Remove drugs that reduce intestinal motility
prevention of paralytic ileus
- avoid IV opioids
- Early ambulation, initiation of clear liquid diet
- Gum chewing - chewing stimulates vagus nerve = promotes peristalsis = release of normal GI tract hormones
pathophys of small bowel obstruction
- impairment in normal flow of intraluminal contents
-
Mechanical obstruction - extrinsic/intrinsic obstacle prevents progression of intestinal contents
- Simple/partial obstruction occludes lumen only
- Full with strangulation impairs blood supply = necrosis of intestinal wall
- Obstruction = progressive dilation of intestines proximal to blockage, while distal to the blockage the bowel will decompress
- Activity of smooth muscle of small bowel increases in an attempt to propel contents past obstruction
- Swallowed air/gas from bacterial fermentation can accumulate, adding to bowel distention
- normal absorptive function lost, and fluid sequestered into bowel lumen and ongoing emesis = additional loss of fluids = hypovolemia
- Bacterial overgrowth can also occur in proximal small bowel, which can cause emesis to become feculent
- Excessive dilation = compressed intramural vessels of the small intestines
— Reduced Perfusion to wall
— tissue ischemia = necrosis and perforation