Malabsorption

Tory Davis, PA-C

To Be Covered

 Malabsorption overview  Small bowel bacterial overgrowth  Carbohydrate intolerance  Celiac Disease  Short Bowel Syndrome  Not covered in this lecture: tropical sprue, Whipple’s disease, secondary causes…look-em-ups

Malabsorption

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

Malabsorption causes…

 Increased fecal excretion  Nutritional deficiencies  – – – – Common GI symptoms: – – Diarrhea Steatorrhea (>6g/d of fat …hallmark of malabsorption) Abdominal bloating Gas Weight loss Other specific s/s with each malabsorbed nutrient

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…

Work-up



If you suspect specific cause, test for it

– Details to follow, and more details from Brenda ’s 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)

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)

Causes of Malabsorption

Bacterial Overgrowth Syndrome

 Usually secondary to anatomic alterations or motility disorders (congenital or acquired) that promote stasis of intestinal contents  Normal small bowel has <10 5 bact/mL  Low count maintained by peristalsis, gastric acid, mucus, intact ileocecal valve function

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

Bac-t Overgrowth Dx

 Frequently, empiric antibiotic therapy resulting in improvement is basis for diagnosis …but abx can worsen many conditions on the ddx  Better: quantitative culture of intestinal fluid. Look for bac-t count>10 5 /mL  Or C-xylose breath test (less invasive)

Bact Overgrowth Tx

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

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)

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

Lactose intolerance

 So, 75% of the world adult population lacks lactase, and we call it abnormal …

Secondary Lactase Deficiency

 Seen with small bowel mucosal damage, such as in

celiac disease

, acute small bowel infections, tropical sprue

Dx/Tx

 Dx by: – – – Careful hx Dietary challenge H 2 breath test  Tx with: – – Lactose avoidance Lactase supplements – Ca + supplements

Celiac Disease

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

Celiac

 Hereditary insensitivity to gliadin fraction of gluten  Gluten-sensitive T cells activated by exposure, cause inflammatory response …leads to mucosal villous atrophy and crypt hyperplasia  N. America 1/5000, (1/150 in SW Ireland)  Female 2:1 male

Presentation

 There is no typical 

Infants

– – Sx appear after cereals intro ’d FTT (failure to thrive), anorexia, pallor, hypotonia, abdominal distention 

Older kids

– Anemia, growth delays, anorexia, diarrhea

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%)



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

Small Bowel Biopsy

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

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)

Prognosis & Complications

 Prog 10-30% mortality without tx  Complications: – Intestinal lymphomas – Refractory disease – Increase in other GI malignancies

Short Bowel Syndrome

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

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

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

SBS Tx

 Small feedings  Anti-diarrheals  TPN if needed