Malabsorption

Question 1

Signs of malabsorption (usually in children)

Answer 1

• Malodorous (bad smelling) stool
• Chronic diarrhea (but many malabsorptive pts do not have diarrhea)
• Failure to thrive
• Weight loss
• Subnormal growth
• Severe malabsorption: edema, pot belly, decreased muscle mass, rickets, excessive bruising/bleeding

Question 2

Carbohydrate malabsorption 1

Answer 2

• Can be due to a number of etiologies: excessive intake, mucosal damage, short bowel syndrome, congenital nz/transport deficiencies
• Typically it is the mucosal phase of digestion that is defective
• In most of these cases the children have dietary carbohydrate intolerance (i.e. lactose) secondarily, due to intestinal damage and lactase nonpersistance (lactase nz starts to decrease at an early age)

Question 3

Carbohydrate malabsorption 2

Answer 3

• Rarely congenital deficiencies cause carbohydrate intolerance
• Since carbs are osmotically active there is loose, watery stools, diarrhea, dehydration, and increased gas production (due to fermentation of carbs by colonic bacteria)
• Can be Dx via hydrogen breath test

Question 4

Causes of malabsorption

Answer 4

• CF
• Chronic cholestasis
• GI surface injury: celiac, crohn’s, short bowel, infectious/post-infectious diarrhea, bacterial overgrowth, congenital nz deficiencies
• Abnormal lymphatic drainage

Question 5

CF

Answer 5

• Leads to defect in intraluminal fat digestion, can cause vits A/D/E/K def
• Mucous plugs up pancreatic and hepatobiliary ducts and leads to fat malabsorption
• Other systems: lung, reproductive
• Sx: lung infections, FTT, bulky loose stools, cholestasis, pancreatitis, edema, rectal prolapse, sinusitis, nasal polyps, digital clubbing, meconium ileus (meconium obstructing ileum)
• Dx via chloride sweat test and DNA screens
• Absence of trypsin in stool indicates pancreatic insufficiency

Question 6

Other causes of pancreatic insufficiency (rare)

Answer 6

• Shwachman-diamond syndrome: short stature, MSK abnormalities (BM dysfxn) from hypoplasia and pancreatic insufficiency
• Johanson-blizzard syndrome: deafness, hypothyroidism, malformed teeth, bird beak nose, dry/coarse/sparse hair
• Due to fatty replacement of pancreas, diabetes, GI anomalies

Question 7

Chronic cholestasis

Answer 7

• Any liver disease that can result in fat malabsorption
• Can lead to def of fat-soluble vitamins
• Vit E def: ataxia, hyporeflexia, ocular palsy, hemolytic anemia
• Vit K: reduced coag
• Vit D: osteopenia/rickets
• Vit A: night blindness
• Can see jaundice, hepatomegaly

Question 8

Celiac disease

Answer 8

• Malabsorption due to villous damage, secondary to ingestion of gluten in those who are intolerant
• Is an immune-mediated disease in genetically predisposed individuals
• Classic clinical: pot bell, wasted extremities, bulky stools, irritability
• Fecal alpha1 antitrypsin (FA1AT) is present in stool (should be absent) due to PLE (protein-losing enteropathy), inability to fully absorb protein
• Many serological tests (anti-gliadin IgA, etc)

Question 9

IBD (UC or CD)

Answer 9

• Variable malabsorption picture, can range from lactose intolerance to generalized malabsorption (from full-thickness bowel injury)
• Strictures can lead to bacterial overgrowth
• PLE can be common
• Screening tests: CBC (anemia from inadequate Fe/folate/B12 absorption), high WBC, FA1AT

Question 10

Short bowel syndrome

Answer 10

• Disruption of intestinal anatomy and physiology (shortened SI)
• Bowel loss: necrotizing enterocolitis (NEC), congenital atresia, volvulus, ischemia, trauma, IBD
• Functional: hirschsprung’s disease, pseudo-obstruction congenital malabsorption diseases

Question 11

Infectious and post-infectious diarrhea 1

Answer 11

• Giardia: does not cause bloody diarrhea, but causes intermittent bloating, diarrhea, bulky stools, other malnutrition signs
• Associated w/ natural fresh waters
• Dx by Ag testing in stool
• Cryptosporidium: diarrhea is non-bloody and watery, similar to giardia
• Dx also by stool sample
• Both giardia and cryptosporidium are worse in IgA def pts

Question 12

Infectious and post-infectious diarrhea 2

Answer 12

• Rotavirus: produces toxin that injures proximal small bowel causing watery diarrhea and fever
• Avoid lactose but breast feeding is OK
• Post-infectious diarrhea can be due to new lactose intolerance
• Dx via stool pH (nl is >6, lactose intolerant is <6)
• Intractable diarrhea of infancy: can occur in sound infants w/ diarrhea greater than 2-3 wks
• Malabsorption can be lethal

Question 13

Bacterial overgrowth

Answer 13

• D/os of intestinal peristalsis can result in stasis and bacterial overgrowth
• This can deplete B12 and other vitamins and minerals
• Results in steatorrhea
• Sx: macrocytic anemia, bloating, diarrhea
• Often these pts lack an ileocecal valve (ICV)

Question 14

Abnormal lymphatic drainage

Answer 14

-Results in malabsorption of fat and fat-soluble vitamins

Question 15

Work up of suspected malabsorption

Answer 15

• H&P
• CBC, ESR, chemistry pannel
• Stool exam (for blood/pathogens/pH/PLE/A1AT/trypsin)
• Blood tests: celiac pannel (IgA), CF DNA, fat-soluble vitamins, other vits/nutrients
• Hydrogen breath test