Week3: malabsorption

Question 1

Signs of malabsorption

Answer 1

-malodorous stools
-chronic diarrhea
-failure to thrive
-weight loss
-subnormal growth
SEVERE
-edema
-rickets
-potbelly
-decreased muscle mass
-decreased fat stores
-excessive bruising or bleeding

Question 2

Failure to thrive and workup

Answer 2

-need to categorize whether failure to thrive is due to deficient diet, malabsorption, or abnormal energy utilization
Workup
1. history: dietary intake, family environment, developmental milestones
2. physical exam
-height, weight, head circumference
-findings: anemia, short stature, fat stores, rash, joint swelling, goiter, organomegaly

Question 3

Nutrient absorption

Answer 3

• mostly in the proximal small intestines

- B12 and bile acids in the terminal ileum

Question 4

Causes of defects in fat, carb, and protein digestion

Answer 4

1. Fat -defective intraluminal phase of digestion
   - pancreatic insufficiency due to CF
   - hepatobiliary dysfunction associated with biliary atresia and primary biliary cirrhosis
2. Carbs- usually defective mucosal phase
   - secondary to excess intake, mucosal damage, short bowel syndrome, congenital intestinal trasport/enzyme deficiencies
3. Proteins
   - hypoproteinemia more likely due to deficient dietary intake and excessive intestinal protein loss *protein losing enteropathy
   - celiac, crohn’s, elevated fecal alpha-1-antitrypsin

Question 5

Secretory diarrhea-malabsorption

Answer 5

• can result in malabsorption if severe
• seen in infections, short bowel syndrome, severe GI mucosal injury, secretory tumors
• electrolyte content of stool approaches serum

Question 6

Causes of malabsorption

Answer 6

1. pancreatic disorders
2. chronic cholestasis
3. GI surface injury
   - celiac, crohn’s, short bowel syndrome, infectious and post infectious diarrhea, congenital intestinal enterocyte brush border enzyme deficiencies, bacterial overgrowth
4. abnormal lymphatic drainage

Question 7

GI presentation in CF

Answer 7

• inspissated (thickening by dehydration) plugging by proteinaceous secretions in pancreas
• bulkly loose stools in infants, cholestasis, pancreatitis
• 20% of CF patients have meconium ileum -thickened and congested meconium in ileum
• constipation
• Tests of pancreatic sufficiency: stool trypsin (if present, it is good)

Question 8

rare causes of pancreatic insufficiency

Answer 8

1. shwachman diamond syndrome
   - autosomal recessive disorder,
   - lipomatosis of pancreas with congenital pancreatic insufficiency
   - short stature, skeletal abnormalities
2. Johanson-blizzard syndrome
   - fatty replacement of pancreas
   - GI anomalies: imperorate anus
   - birdbeak nose, deafness, hypothyroidism

Question 9

Chronic cholestasis

Answer 9

• any hepatobiliary disorder that results in chronic cholestasis can cause fat malabsorption
• can have fat-soluble vitamin deficiencies
• Vit E def. -ataxia, hyporeflexia, ocular palsy, hemolytic anemia
• Vit K: reduced coag factors
• Vit D: rickets, osteopenia
• VIt A: night blindness
• Presentation: jaundice since infancy
• children in early infancy have biliary atresia
• Alagille syndrome: cholestasis, congenital heart disease, short stature, characteristic facies, skeletal/rib abnormalities

Question 10

Causes of malabsorption due to GI mucosal surface injury

Answer 10

1. Celiac disease

2. Crohn’s disease

Question 11

Infectious diarrhea causing malabsorption

Answer 11

1. Giardia -non bloody diarrhea
2. Cryptosporidium -watery and non bloody diarrhea. affects immunocompromised
3. post-infectious diarrhea
   - sustained acute diarrheal illness
   - lactose malabsorption can occur in patients with repetitive diarrhea, previous GI disease, live in developing country
   - intractable diarrhea of infancy: longer than 2-3 weeks
4. Rotavirus: injury of brush border by toxin. early childhood.

Question 12

Congenital intestinal enterocyte brush border enzymes deficiency

Answer 12

• presentation: watery diarrhea, bloating, abdominal distension, acidosis, dehydration after birth
• rare diseases
• stools test positive for acid and reducing substances
• hydrogen breath test
• lactose intolerance: nonresistance of lactase after childhood is normal. Secondary intolerance is common, loss of lactase secondary to other diseases. Congenital is rare.

Question 13

Primary intestinal lymphangiectasia

Answer 13

• findings of malabsorption of long chain fatty acids, low fat soluble vitamin levels, lymphopenia, abnormal lymphatic imaging studies
• there is abnormal draining of lymphatics.
• short and medium chain fatty acids can be absorbed and transported directly through mesenteric venous blood to liver

Question 14

secondary intestinal lymphangiectasia

Answer 14

-results as a consequence of many disorders, e.g. Crohn’s, mycobacterial infections, radiation enteritis, lymphatic turbos, other neoplasms, heart disease

Question 15

Screening tests for Malabsorption

Answer 15

Blood
-Celiac panel with IgA level
-CF DNA mutations in CFTR
-fat soluble vitamin levels
-other vitamin levels
Stool
-FA1AT for PLE- celiac, crohns
-trypsin
-stain for fat
-24 hour fecal fat
-pH
-Clinitest: tests for reducing substances in urine. (lactose malabsorption, or other sugars)
Other
-sweat chloride test for CF
-Hydrogen breath test for carb malabsorption