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  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