Assessment of Malabsorption and Celiac Flashcards
Malabsorption vs maldigestion
Maldigestion: defective hydrolysis of nutrients
Malabsorption: defective mucosal absorption
4 types of problems from a luminal defect
Solubilization
Digestion
Liberation
Chemical changes
Iron can only be absorbed in what form?
Fe2+
Citrus can convert from 3+ to 2+
What is absorbed in the proximal small intestine?
8
Fat Sugars Peptides and amino acids Iron* Folate Calcium Water Electrolytes
What is absorbed in the middle small intestine? (5)
Sugars Peptides and amino acids Ca Water Electrolytes
What is absorbed in the distal small intestine? (4)
Bile salts
Vitamin B12
Water
Electrolytes
What is absorbed in the colon? (4)
Water
Electrolytes
Medium chain triglycerides
Amino acids
How can the mucosal adapt to changes?
Increases in the number of villus enterocytes and in villus height
Absorptive capacity may be enhanced up to 5-fold
3 major ways to clinically assess malabsorption
Anthropometry
Biochemical
Screening tools
Anthropometry assessments for malnutrition
BMI Height, weight Hip to waist ratio Skinfold (subcutaneous fat) Muscle bulk
2 screening tools for malnutrition
Subjective global assessment (includes physical exam - sc fat, edema, muscle bulk)
Mini-nutritional assessment (includes BMI or sc fat)
Mild/moderate malnutrition
Moderate weight loss (5-10%) Compromise in food intake Continued weight loss Progressive functional impairment Moderate stress
Severe malnutrition
Severe weight loss (> 10%)
Poor nutrient intake
Progressive functional impairment
Muscle wasting
Hydrogen breath test
Want to see if they can digest lactose
Measure baseline, ingest lactose, then blow into bag every 30 mins and see how much gas they produce
If you cannot digest lactose you turn it into gas
Quantitative fecal fat
Collect stool for 24 hours
Can detect pancreatic insufficiency
Why would you measure fecal elastase?
Faster way of assessing pancreatic insufficiency
Higher sensitivity but low specificity
How is vitamin B12 absorbed?
Ingested bound to food Salivary R protein liberates it Trypsin digests R protein B12 binds to intrinsic factor Absorbed with IF in ileum Trancobalamin 2 transports B12 to liver
Schilling Test
Step 1
Confirm B12 malabsorption
Give large dose IM non-labelled B12 to saturate the carriers
Give small dose oral radiolabelled B12 that is absorbed by the intestine
Measure radiolabelled B12 in urine
Malabsorption if < 7-10% of oral dose recovered
Schilling Test
Step 2
Confirm sites of B12 absorption
Give oral intrinsic factor (if it helps, they have pernicious anemia)
Give pancreatic enzyme (if it helps, they have pancreatic insufficiency)
Give antibiotics (if it helps, they have a small intestinal bacterial overgrowth that is eating all their B12)
What is the genetic susceptibility for celiac disease?
HLA-DQ2 or HLA-DQ8
Classic vs atypical celiac disease
Classic: gluten-sensitive enteropathy and malabsorption
Atypical: gluten-sensitive enteropathy and extraintestinal symptoms and signs (short stature, anemia, osteoporosis, and infertility)
Silent vs latent vs potential celiac disease
Silent: gluten-sensitive enteropathy found after a serologic screening in asymptomatic patients
Latent: normal villus architecture on a gluten-containing diet but have had/will have gluten-sensitive villus atrophy
Potential: never had a biopsy consistent with celiac disease but show immunologic abnormalities characteristic for the disease. Patients often have a genetic predisposition
Refractory celiac disease
Symptomatic
Severe small intestinal villus atrophy but does not respond to at least 6 months of a strict gluten-free diet
4 histological findings in classic celiac disease
Villus atrophy
Crypt hyperplasia
Enterocyte disarray
Inflammatory infiltrates
Where in the small intestine does celiac affect?
Proximal > distal
Malabsorption in celiac
Decreased absorption ability (increased stool volume and osmotic load)
Secretion of electrolytes into lumen
Decreased release of bile acid and pancreatic enzymes in response to meals
Unabsorbed bile salts
3 things to look for on serology for celiac
Anti-tTG IgA
Anti-Endomysial antibody
Anti-gliadin antibodies (IgA, IgG)
Treatment for celiac
Gluten free diet
Dietary supplementation (for vitamins)
Monitor associated diseases
