Term
| Why do disorders of maldigestion and malabsorption commonly occur sub-clinicaly before symptoms of diarrhea and nutrient deficiency develop? |
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Definition
Intestinal REserve
- Redundancy in both presence of many digestive enzymes as well as location along GI tract.
**Diarrhea is a SYMPTOM, not a diagnosis, - follow with 24-36h fast** |
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Term
True or False:
No significant maldigestion problems are associated with loss of oral amylase. |
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Definition
True!
Intestinal amylase can compensate |
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Term
| How can damage to the stomach impact digestion/absorption? |
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Definition
No absorption takes place here (still, Vitamin B12 deficiency and Zollinger-Ellison are associated with gastric function), but mechanical breakdown (contractions) and digestion/emulsion does occur here.
Damage will not cause maldigestion, because of intestinal redundancy, but you will EAT SMALLER MEALS. |
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Term
| Which two malabsorption syndromes are associated with gastric function? |
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Definition
1) Vitamin B12 (cobalamin) deficiency
- Intrinsic factor produced by parietal cells protects B12 until terminal illeal absorption.
- Associated with pernicious anemia and neuro symptoms.
2) Zollinger-Ellison syndrome
- Gastrin secreting tumor of stomach and/or pancreas with increased acid secretion and duodenum issues that prevent absorption. |
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Term
| What stimuli activate pancreatic, intestinal and biliary secretions int he upper small intestine (duodenum) |
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Definition
Site of most digestion and much of absorption
1) Mechanical distention- reflex increase in motility and ACh secretion
2) Osmolarity (protein and fat)- stimulate CCK and cause pancreatic enzyme release
3) Low pH (4-6)- stimulates Secretin secretion, which elicits pancreatic HCO3- release to neutralize pH and allow enzymes to function. |
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Term
| What are the primary and secondary causes of the only significant disorder of CHO malabsorption? |
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Definition
Lactose malabsorption (Diarrhea, abdominal pain, cramps and flatus)
1) Primary
- Absence of lactase (birth or with age)
2) Secondary
- Loss of lactase with small intestinal mucosal disease, or brush border enzyme deficits. |
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Term
| What minerals and nutrients are actively absorbed in the proximal small intestine (duodenum) |
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Definition
Disrupted with gastric bypass surgery
1) Calcium (osteoporosis)
2) Iron (cup nails)
3) Niacin (pallegra)
4) Fat soluble vitamine (ADEK) |
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Term
| What are the 3 common causes of impaired fat digestion/absorption in the proximal small intestine? |
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Definition
1) Chronic pancreatitis (MOST COMMON) with steatorhea
2) Zollinger-Ellison - pH is too low for enzymatic activation
- Treat with PPi or surgery for tumor
3) Biliary function
- Deceased fat absorption (micelle formation impaired)
- Gallstones often cause pancreatitis |
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Term
| What are the causes of impaired fat digestion/absorption in the Jejunum and Illeum? |
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Definition
1) Jejunum (fatty acid, diglyceride absorption and passive bile acid absorption): Celiac disease
2) Ileum (Vitamine B 12 and folate absorption and active bile acid reabsorption
- CD or UC, bowel resection causes less bilea cid resorption and bile acid diarrhea (more delivered to colon)
**Give cholestyramine**
- Intestinal bacterial overgrowth (surgery or aggressive antibiotic for functional stasis that causes overgrowth) |
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Term
| Describe the basic strategy of a malabsorption workup. |
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Definition
1) Determine secretory, malabsorptive/omsotic or both
- 24h fast (malabsorptive/osmotic will improve)
2) If Malabsorptive
- most common CHO is lactose intolerance (H2 breath test and h/x)
- Test for high pancreatic enzymes (pancreatitis)
- Test for B12, folate, minerals
- Steatorrhea
3) If Secretory
- Stool analysis (osmolality), serum electrolytes, mucosal biopsy and serum microbiology. |
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Term
| What are the 2 clinically significant causes of INCREASED absorption? |
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Definition
1) Hemochromatosis- increased iron absorption
2) Wilson's Disease- Increase copper ion absorption. |
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