Malabsorption

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Malabsorption

• Tory Davis, PA-C

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To Be Covered

• Malabsorption overview
• Small bowel bacterial overgrowth
• Carbohydrate intolerance
• Celiac Disease
• Short Bowel Syndrome
• Not covered in this lecture tropical sprue,
  Whipples disease, secondary causeslook-em-ups

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Malabsorption

• Inadequate assimilation of dietary substances due
  to defects in
• Digestion
• Absorption
• Transport
• Can affect micronutrients (vits and minerals) or
  macronutrients (protein/carb/fat)?

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Malabsorption causes

• Increased fecal excretion
• Nutritional deficiencies
• Common GI symptoms
• Diarrhea
• Steatorrhea (gt6g/d of fathallmark of
  malabsorption)?
• Abdominal bloating
• Gas
• Weight loss
• Other specific s/s with each malabsorbed nutrient

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How to figure it out

• Suspect malabsorption in all patients with
  chronic diarrhea, wt loss, anemia
• Check hx for clues
• Hx acute pancreatitis? Think chronic panc
• Hx lifelong diarrhea exac by gluten? Rash, too?
  Think celiac disease
• Milk makes them fart? Think lactose intolerance
• Had most of their small bowel removed? Think
  short bowel syndrome! Okay, duh

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Work-up

• If you suspect specific cause, test for it
• Details to follow, and more details from Brendas
  lab lectures
• And/or check CBC (anemia), ferritin, lytes
• Confirm malabsorption
• 72 h fecal fat collection
• Sudan III stool stain for fat
• D-xylose test (assesses mucosal integrity to
  differentiate between mucosa and pancreatic
  etiology)?

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Diagnosis of Malabsorption

• Endoscopy with small bowel bx
• Culture small bowel aspirate for bac-t overgrowth
• Small bowel xrays to look for anatomical
  conditions that may predispose to bac-t
  overgrowth (fistulas, surgical blind loops,
  strictures, ulcerations)?
• Schilling test (B12)?

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Causes of Malabsorption
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Bacterial Overgrowth Syndrome

• Usually secondary to anatomic alterations or
  motility disorders (congenital or acquired) that
  promote stasis of intestinal contents
• Normal small bowel has lt105 bact/mL
• Low count maintained by peristalsis, gastric
  acid, mucus, intact ileocecal valve function

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What Extra Bacteria Do

• Consume nutrients, especially B12 and carbs
• B12 (cyanocobalamin) deficiency
• Calorie deprivation/weight loss
• Produce folate, so this is NOT a cause of folate
  deficiency (folate def causes macrocytic anemia)
• Deconjugate bile salts
• Fat malabsorption
• Steatorrhea and diarrhea

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Bac-t Overgrowth Dx

• Frequently, empiric antibiotic therapy resulting
  in improvement is basis for diagnosisbut abx can
  worsen many conditions on the ddx
• Better quantitative culture of intestinal fluid.
  Look for bac-t countgt105/mL
• Or C-xylose breath test (less invasive)?

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Bact Overgrowth Tx

• 10-14 days oral abx
• Tetracycline
• Amox/clavanulate
• Cephalexin
• TMP/SMX
• Metronidazole
• Correct underlying condition
• Correct nutritional deficiencies

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Carbohydrate Intolerance

• Inability to digest certain carbs due to lack of
  one or more enzymes
• Sx watery diarrhea, abdominal distention,
  flatulence, nausea, borborygmi, abd cramping
  (hooray for lactaid!)?
• Etiology
• Acquired (primary)?
• Secondary
• Congenital (rare)?

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Lactase Deficiency

• Primary adult hypolactasia
• Most common carb intolerance
• Lactase normally in high levels in neonates but
  decrease after weaning in most ethnic groups
• 80 blacks and hispanics
• Near 100 Asians
• Only 15-20 Caucasians

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Lactose intolerance

• So, 75 of the world adult population lacks
  lactase, and we call it abnormal

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Secondary Lactase Deficiency

• Seen with small bowel mucosal damage, such as in
  celiac disease, acute small bowel infections,
  tropical sprue

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Dx/Tx

• Dx by
• Careful hx
• Dietary challenge
• H2 breath test
• Tx with
• Lactose avoidance
• Lactase supplements
• Ca supplements

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Celiac Disease

• Aka
• Celiac Sprue
• Non-tropical sprue
• Gluten Enteropathy
• Immunologically mediated disease caused by
  intolerance of gluten, which causes mucosal
  inflammation and malabsorption

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Celiac

• Hereditary insensitivity to gliadin fraction of
  gluten
• Gluten-sensitive T cells activated by exposure,
  cause inflammatory responseleads to mucosal
  villous atrophy and crypt hyperplasia
• N. America 1/5000, (1/150 in SW Ireland)?
• Female 21 male

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Presentation

• There is no typical
• Infants
• Sx appear after cereals introd
• FTT (failure to thrive), anorexia, pallor,
  hypotonia, abdominal distention
• Older kids
• Anemia, growth delays, anorexia, diarrhea

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Adults

• Anorexia, weakness,
• Diarrhea, steatorrhea,
• Anemia
• Glossitis, angular stomatitis, aphthous ulcers
• Decreased fertility
• Lactose intolerance (Why?)?
• Will lactose avoidance help the sx?
• Evidence of ? Ca/vit D (like what?)?
• Dermatitis herpetiformis (10)?

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Diagnosis

• Clinical suspicion
• Use clues like unexplained Fe deficient anemia
• FHX
• Labs
• 72 hr fecal fat
• D-xylose absorption test
• Tissue transglutaminase (IgA)?
• Anti gliaden antibody (IgA)?
• Anti reticulin antibody (IgA)?
• Total IgA (check to make sure there is no IgA
  deficiency)?
• Antibody levels decrease with gluten-free diet,
  so you can use this to determine if the pt is
  really following the diet

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Small Bowel Biopsy

• Not specific
• Villous atrophy
• Lack of or shortening of villi
• Increased epithelial cells
• Crypt hyperplasia

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Celiac Treatment

• Gluten free diet
• No wheat, rye, barley or anything that has gluten
  in it
• No breads, bagels, pastries, pasta and pizza
• Gluten used as thickener frequently, so need
  education to facilitate avoidance
• Must do dietitian referral, advise support group
• Sx will resolve in 1-2 weeks (usually)?

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Prognosis Complications

• Prog 10-30 mortality without tx
• Complications
• Intestinal lymphomas
• Refractory disease
• Increase in other GI malignancies

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Short Bowel Syndrome

• Malabsorption due to extensive small bowel
  resection (often because of Crohns, mesenteric
  infarction, radiation enteritis)?
• Symptom severity depends on length and function
  of remaining bowel
• Diarrhea and nutritional deficiencies

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Jejunum

• Primary digestive and absorptive site for most
  nutrients
• BUT
• If removed, the ileum will adapt by changing
  villous structure
• Gradual clinical improvement as adaptive process
  continues

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Ileum

• Primary site for B12 and bile acid absorption
• No compensatory mechanism for loss of ileum
• Malabsorption of fats, fat-soluble vitamins, and
  B12
• Bile acids in large intestine cause secretory
  diarrhea

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SBS Tx

• Small feedings
• Anti-diarrheals
• TPN if needed