Ray - Malabsorption Flashcards
1
Q
What is the difference b/t malabsorption and maldigestion?
A
- MALABSORPTION: impaired absorption of nutrients
- MAL-DIGESTION: impaired digestion of nutrients
- Clinically, this distinction does not matter -> simply refer to malabsorption
2
Q
What are the 3 steps to normal nutrient absorption?
A
- Luminal and brush border processing
- Absorption into intestinal mucosa
- Transport into the circulation
3
Q
What is the difference b/t global and partial malabsorption?
A
- GLOBAL: reduced mucosal involvement or reduced absorptive surface
1. Not having enough bowel, or defect throughout the bowel - PARTIAL: interferes with the absorption of specific nutrients
1. B12: need intrinsic factor from stomach (gastrectomy) and terminal ileum (Crohn’s)
2. Bile acids: terminal ileum
3. Fe2+, Mg2+, Ca2+, absorbed in duodenum (2+ ions): deficiencies in some bypass surgeries
4
Q
What are the clinical features of global malabsorption?
A
- CLASSIC: diarrhea
1. Pale, voluminous, foul-smelling stools
2. Weight loss - “Classic” symptoms are actually quite uncommon, and the more SUBTLE SYMPTOMS are:
1. Anorexia
2. Flatulence
3. Abdominal distention
4. Borborygmi: rumbling, gurgling noise made by movement of fluid or gas in the intestines
5. Iron deficiency or osteopenia - NOTE: can mimic IBS
5
Q
What are the 8 categorical causes of malabsorption?
A
- Gastric disease
- Pancreatic disease
- Liver/biliary disease
- Lymphatic disease
- Intestinal disease
- Neuroendocrine tumors
- Endocrine causes
- Systemic disease
6
Q
What are some gastric causes of malabsorption?
A
- Atrophic gastritis
- Auto-immune gastritis: pernicious anemia
- Gastric resection
7
Q
What are some pancreatic causes of malabsorption?
A
- Congenital enzyme deficiency
- Pancreatic insufficiency:
1. Chronic pancreatitis
2. Cystic fibrosis
8
Q
What are some liver and biliary causes of malabsorption?
A
- Inborn errors of bile transport
- Cirrhosis
- Biliary tumors
- Primary and secondary sclerosing cholangitis (can occur in Crohn’s)
9
Q
What are some lymphatic causes of malabsorption?
A
- Primary intestinal lymphangiectasia: pathologic dilation of lymph vessels
- Secondary:
1. Lymphoma
2. Solid tumors
3. Thoracic duct trauma or obstruction
10
Q
What are some intestinal causes of malabsorption?
A
- Amyloidosis
- Celiac sprue, tropical sprue, food allergies
- Crohn’s
- Graft vs. host disease
- Intestinal infections
- Radiation enteritis
- MANY others
11
Q
What are some NE tumor causes of malabsorption?
A
- Carcinoid syndrome
- Glucagonoma
- ZE syndrome: gastrinoma
- Somatostatinoma
12
Q
What are some endocrine causes of malabsorption?
A
- Addison’s disease
- Diabetes
- Hypothyroidism
13
Q
What are some systemic causes of malabsorption?
A
- Scleroderma
- Lupus
- Neurofibromatosis
14
Q
How do you begin to determine the cause of pt’s malabsorption?
A
- HISTORY
1. Alcohol use
2. Prior surgeries
3. Relation of symptoms to diet
4. Abdominal pain
5. History of ulcers
6. Diabetes
7. Medications
15
Q
What labs should you look at in pt with malabsorption?
A
- CBC
- Iron, B12, folate
- Albumin
- Ca, Vit. D
16
Q
What is the most commonly used indicator of global malabsorption? Tests?
A
- FAT: most complex process of absorption of the macronutrients, so tends to be most sensitive to interference from disease process
1. Most calorically dense macronutrient, so its malabsorption is a critical factor in the weight loss often seen in malabsorptive disorders - TESTS:
1. Qualitative: Oil red “O”/Sudan stain
2. Quantitative: 72-hr stool fat collection (gold standard, but rarely done in practice)
17
Q
How does the 72-hr stool fat assessment work?
A
- QUANTITATIVE: >6g/d of fat is pathologic bc in stool fat excretion in healthy ppl usually <6g/d
- Pts w/steatorrhea usually have >20g daily: modest INC in fecal fat does not diagnose steatorrhea
- GOLD STANDARD, but rarely done in practice (compliance issues; cumbersome and messy)
- NOTE: stool fat remains constant with high fat diets, even >125g of fat daily
18
Q
What is the qualitative stool fat assessment?
A
- Oil red “O”/Sudan stain: stain for fat globules from a spot stool sample can detect >90% of pts with steatorrhea
- Sudan stain: fat stains orange (can stain all kinds of colors, according to Dr. Gupta)
- See attached image
19
Q
Besides fat, what other macronutrient test can be used to assess malabsorption?
A
- CARBOHYDRATES: can rely on fermentation of undigested carbs by intestinal bacteria, or direct measurement of absorption of specific nutrients
- Examples: lactose tolerance test and several breath tests that measure hydrogen or radioactive isotopes from sugars containing radionuclide carbon analogues
20
Q
What “other” diagnostic tests (incl. radiologic) can be done for malabsorption (aside from fat, carbs)?
A
- Upper endoscopy with biopsy
- Colonoscopy with ileal intubation (or biopsy)
- ERCP (endoscopic retrograde cholangio-pancreatography): images of bile & pancreatic duct
- Radiologic studies:
1. CT scan
2. Small bowel follow-through: x-ray that follows passage of barium through stomach and into the small intestine
3. MRCP: magnetic resonance cholangio-pancreatography uses MRI to visualize biliary and pancreatic ducts in non-invasive manner
21
Q
What might this be?
A
- CELIAC SPRUE: notice the “scalloping”
- Doesn’t make the dx: need to take a biopsy
22
Q
What is going on here?
A
- Terminal ileum in normal (left) vs. CROHN’s (right)
23
Q
What might this be?
A
- CHRONIC PANCREATITIS: this is an ERCP (images taken while patient is on a fluoroscopy table)
- Scope can be seen on B: filling pancreatic duct with dye
- Dilated, strictures, torturous: probably chronic pancreatitis
24
Q
What do you see here?
A
- EUS of normal pancreas vs. CHRONIC PANCREATITIS: dilated pancreatic duct, and body of pancreas calcified, much more heterogeneous
- US from inside the digestive tract
- Can biopsy mass through this endoscope too
25
Q
Name 4 common causes of malabsorption.
A
- Celiac sprue
- Lactose intolerance
- Bacterial overgrowth
- Chronic pancreatitis
26
Q
What is celiac sprue? Diagnosis?
A
- Autoimmune disorder of small bowel due to intolerance of gluten
1. Leads to global malabsorption, but symptoms can be subtle - DX: tissue transglutaminase IgA
1. Total IgA: if pan-deficient in IgA, will not have TTG IgA (and have 5x risk)
2. Small bowel biopsy -> confirms diagnosis, regardless of the results of these first 2 tests
3. Can be diagnosed with nothing more than iron deficiency anemia - Good to have dietitian help in tx of these pts
- Susceptible to bone loss
- NOTE: these tests must be done while pt is taking gluten in their diet
27
Q
What condition do you see here? Describe the characteristic histopathology and dx technique.
A
- TOP: normal intestinal mucosa
- BOTTOM: celiac disease
- Biopsy specimens from duodenum are generally diagnostic in celiac disease
- Histopathology is characterized by:
1. INC #’s of intraepithelial CD8+ T lymphos (intraepithelial lymphocytosis)
2. Crypt hyperplasia
3. VILLOUS ATROPHY - Probably takes awhile for the severe appearance on front of card, so INC #’s of CD8+ T-lymphos in tops of villi is what pathologist looks for -> see attached image
28
Q
What is going on here? HIsto? Associated GI condition?
A
-
Dermatitis herpetiformis: red, itchy, punctate lesions
1. Clefts filled with neutrophils (see attached image of histo) - Associated with CELIAC DISEASE
29
Q
What do you see here?
A
- Enteropathy-associated T-cell lymphoma: sheet of lymphos that eat up crypts/glands
- Associated with CELIAC DISEASE
30
Q
What is lactose intolerance? Symptoms and epi?
A
-
Intolerance of lactose-containing foods: primarily dairy products
1. Caucasians have abnormal persistence of lactase: only during childhood in most races (tolerance wanes with age) - SYMPTOMS: bloating, abdominal pain, diarrhea, flatulence after ingestion of dairy products
- EPI: only 7-20% of Caucasians
1. 80-95% of Native Americans
2. 60-75% of Africans
3. Up to 90% in parts of Asia
31
Q
How does lactose digestion work?
A
- Lactose hydrolyzed by intestinal lactase to glu + galactose, and these 2 monosaccharides are then absorbed by intestinal mucosa
1. Lactose not absorbed in the small bowel can be absorbed in the colon - In colon, lactose converted to short-chain fatty acids (SCFA’s) + hydrogen gas -> the fatty acids are absorbed by the colonic mucosa
1. Production of hydrogen by colonic bacteria basis of the lactose breath hydrogen test used to diagnose lactose maldigestion
32
Q
How is lactose intolerance diagnosed?
A
- History: this alone can be just fine to dx
- Lactose tolerance test
- Lactose hydrogen breath test
33
Q
How does the lactose tolerance test work?
A
- Oral admin of 50g lactose, and blood glu levels monitored at 0, 60, and 120 minutes
- Positive test = blood glu INC <20mg/dL + devo of symptoms
- NOTE: this test is “not done”
34
Q
How does the lactose hydrogen breath test work?
A
- Easy to perform, so it has largerly replaced the lactose tolerance test
- Give 25g oral lactose -> breath hydrogen measured at baseline and 30-min intervals for 3 hrs
1. Hydrogen values >20 ppm are diagnostic - NOTE: you can even order these tests over the internet and have them mailed to your home (see attached image)
35
Q
What is the tx for lactose intolerance?
A
- Avoidance of dairy products
- Replacement of lactase
- Supplemental Ca and Vit. D
36
Q
What is small bowel bacterial overgrowth (SBBO)? Associations?
A
- Condition in which non-native and/or native bacteria are present in INC #’s
1. Results in excessive fermentation, inflam, or malabsorption
2. Small bowel is relatively sterile: ileocecal valve, motility, pylorus keep bacterial growth here to a minimum - Associated with:
1. Anatomic abnormalities: surgical loops (blind loops of bowel), strictures
2. Abnormal small bowel motility: DM, scleroderma, radiation enteritis
3. Abnormal communication in small bowel: fistulas, don’t have ileocecal valve, pylorus
4. Others: chronic pancreatitis, cirrhosis, ESRD, TPN use in children
37
Q
How is SBBO diagnosed?
A
- Suspected by history
- Can give empiric trial of antibiotics: improvement can last months
-
Carbohydrate breath tests: can use lactulose, glucose, D-xylose (2 peaks = (+) result)
1. (+) results will see early peak from hydrogen production in small bowel, then later peak from hydrogen production in colon -> normal result is peak only after 2-3 hours in colon
38
Q
How is SBBO treated?
A
-
Trial of antibiotics: can treat with 7-10 day course with lasting results
1. Rifaxamin is a non-absorbed, expensive AB: few side effects, and low risk of resistance -
Treat underlying disorder:
1. Motility agents
2. Surgical correction
39
Q
What is chronic pancreatitis? Symptoms?
A
- Condition of progressive inflammatory changes leading to structural damage
- Contrasts with acute pancreatitis: recurrent bouts of acute can progress to chronic
- SYMPTOMS: abdominal pain
1. Pancreatic insufficiency: does not occur until 90% of pancreatic function is lost -> fat malabsorption, diabetes
40
Q
How is chronic pancreatitis diagnosed?
A
- HISTORY: chronic alcohol abuse
- FECAL ELASTASE: most sensitive and specific, esp. in early phases of pancreatic insufficiency
1. <200mcg/g suggestive of pancreatic insufficiency
2. Independent of pancreatic enzyme replacement tx, and require only single random stool sample - IMAGING studies: CT, MRI, MRCP, EUS
41
Q
How is chronic pancreatitis treated?
A
- Cessation of alcohol intake: hardest part
- Pain management
- Enzyme replacement: pill forms
- Surgical procedures: to relieve blocked pancreatic duct (not very common)
42
Q
What is Whipple disease? Dx? Histo? Tx?
A
- Rare, multivisceral chronic disease presenting with malabsorption, lymphadenopathy, and arthritis
1. Middle-aged pts with weight loss, diarrhea, pain, and arthropathy -> when you see this, think Whipple
2. Test of choice is biopsy of small bowel - HISTO: foamy macros and large #’s of argyrophilic rods in lymph nodes
1. G(+) actinomycete (Tropheryma whippelii) - TX: prolonged course of AB’s (1-2 years of tx)
43
Q
What is going on here? Pathogenesis? Stain?
A
- Dense accumulation of distended, foamy macros in small intestinal lamina propria -> Whipple’s
- Clinical symptoms bc organism-laden macros accumulate in small intestinal lamina propria and mesenteric lymph nodes, causing lymphatic obstruction
1. Malabsorptive diarrhea due to impaired lymphatic transport - PAS positive and diastase resistant (see attached image)
44
Q
What is this?
A
Normal duodenum
45
Q
What is going on here?
A
-
Intestinal TB: foamy macros and PAS-positive organism -> similar appearance to Whipple’s
1. Acid-fast stain can be helpful bc mycobacteria stain (+), but T. whippelii do not - NOTE: mycobacterium avium complex (MAC) consists of two species -> M. avium and M. intracellulare
46
Q
Which of the following is only absorbed in the terminal ileum?
A. Calcium
B. B12
C. Bile salts
D. Iron
A
B. B12 and C. Bile salts
47
Q
Which of the following is the best test to screen for celiac sprue?
A. Lactose hydrogen breath test
B. SBFT: a fluoroscopic technique designed to obtain high resolution images of the small bowel
C. Tissue Transglutaminase IgA
D. MRCP
A
C. Tissue Transglutaminase IgA (if +, then small bowel biopsy)
48
Q
Which of the following does NOT predispose to SBBO?
A. Diabetes
B. Pulmonary HTN
C. Scleroderma
D. Prior bowel surgeries
A
B. Pulmonary HTN
- NOTE: diarrhea may be fairly common in diabetes due to meds (Metformin), overgrowth, etc.
49
Q
What is tropical sprue (at a very basic level)?
A
- Like Celiac disease, but presents with patient who spent more than a few months in the tropics
- May develop several years later
