Malabsorption: Ray Flashcards
Describe the three steps to normal nutrient absorption.
1) Lumenal and brush border processing
2) Absorption into the intestinal mucosa
3) Transport into the circulation
Discuss the difference between global and partial malabsorption and the clinical implications of each.
Global- results from reduced mucosal involvement or reduced absorptive surface. Global deficiency of nutrients.
Partial- only part of the bowel has malabsorptive properties, so certain nutrients will not be absorbed while others are, based on their geographic pattern of absorption. Ex: B12 in the ileum
Describe gastric causes of malabsorption.
atrophic gastritis
autoimmune gastritis
gastric resection
Describe pancreatic causes of malabsorption.
Congenital enzyme deficiency Pancreatic insufficiency (chronic pancreatitis, CF)
Describe liver and biliary causes of malabsorption.
Inborn errors of bile transport
Cirrhosis
Biliary tumors
Primary and secondary sclerosing cholangitis
Describe lymphatic disease causes of malabsorption.
Primary intestinal lymphangectasia
Secondary: lymphoma, solid tumors, thoracic duct trauma or obstruction
Describe intestinal causes of malabsorption.
Amyloidosis Celiac dz Crohn's dz Food allergies Graft vs. host dz Intestinal infections Radiation enteritis Tropical sprue Others...
Describe neuroendocrine causes of malabsorption.
Carcinoid syndrome
Glucagonoma
Z-E syndrome
Somatostatinoma
Describe endocrine causes of malabsorption.
Diabetes
Addison’s dz
Hypothyroidism
Describe systemic causes of malabsorption.
Scleroderma
Lupus
Neurofibromatosis
Malabsorption of ______ is the most commonly used indicator of global malabsorption.
fat
In healthy people, stool fat excretion is usually less than ___ grams/day.
6 grams/day
Steatorrhea is dx’d when stool fat is > ____g/day.
20g/day
Describe the qualitative test for excess fat in stool.
Sudan stain for fat globules has a 90% sensitivity
Describe the tests for evaluating CHO malabsorption.
Can rely on fermentation of undigested CHO by intestinal bacteria.
Direct measurement of the absorption of specific nutrients after a test dose.
Celiac sprue: Etiology Intolerance to? Global or partial malabsorption? Symptoms? Dx? Histology?
Etiology: Autoimmune disorder of small bowel
Intolerance to: gluten
Global malabsorption
Symptoms: range from mimicking IBS to peds pt w/ poor growth/failure to thrive.
Dx: blood test for tissue transglutaminase (tTG) (will be elevated). Test total IgA (deficient). tTG:IgA will be elevated. Small bowel biopsy. Pt needs to be on gluten diet for tests to be revealing. Need to be HLA-2 or HLA-8 positive.
Histo: intraepithelial lymphocytosis (CD8+) at tips of villi. Crypt hyperplasia. Villous atrophy.
Describe dz associations of Celiac dz/sprue?
Dermatitis herpetiformis (subepithelial clefts w/ neutrophilic infiltrate) Enteropathy assoc. T-cell lymphoma. Seen as sheets of lymphocytes "eating up glands".
Describe the symptoms of lactose intolerance.
These pts are highly susceptible to _______ loss.
Bloating, flatulence, abd. pain, diarrhea, after ingesting dairy.
Highly susceptible to bone loss because of lack of Ca++ in diet.
Describe dx of lactose intolerance.
History
Lactose Hydrogen breath test- measured Q30mins x3hrs after baseline 25g lactose. >20ppm = LI
Lactose tolerance test- Give 50g lactose, measure blood glucose (should rise >20mg/dl w/o symptoms) not used
Excessive growth of bacteria in the small bowel can result in:
FIM: fermentation, inflammation, malabsorption
How can you dx small bowel bacterial overgrowth?
How do you tx it?
Dx with:
Hx
Empiric trial of Abx
CHO breathe tests
Tx with:
Rifaxamin x7-10days. Not absorbed. Lasting results.
Treat underlying disorder (motility disorder, surgical correction of anatomical defect)
MC symptoms of chronic pancreatitis:
Abd. pain
Pancreatic insufficiency- Fat malabsorption, diabetes. Does not occur until 90% of function is lost.
What is going on in Whipple’s dz?
Foamy macrophages filled w/ T. whippelii accumulate in small intestinal lamina propria resulting in lymphatic obstruction.
Malabsorptive diarrhea of Whipple dz due to impaired lymphatic transport.
What organism stains positively on PAS/diastase stain that can make it difficult to differentiate it from T. whippelii?
What stain will help differentiate the two?
M. avium/intracellulare
Acid fast stain to differentiate (Mycobact. is pos.)
What are the classic symptoms of Whipple dz?
Middle aged pt. Weight loss Diarrhea Abd. pain *arthropathy* give away!
