TOC   |  GI   

MALABSORPTION SYNDROMES

Suspected in pts with persistent weight loss despite a more than adequate caloric intake.

DX: CBC: anemia, often megaloblasticHypocalcemia, hypomagnesemia, hypoalbuminemia in small intestinal malabsorptionStool smear: fat globules 72 hr stool fat quantitative analysis: > 6gm/dayXylose absorption test: urin. excretion of < 4gm after 5 hrsSmall intestinal x ray: may show mucosa abnormality14C Triolein breath test: + in bacterial overgrowth & ileal dysfunctionSmall intestine per oral biopsyOthers: Bentiromide 500 mg PO test, serum trypsinogen immunoassay, etc.

A. Inadequate digestion

1. Postgastrectomy steaorrhea
2. Deficiency or inactivation of pancreatic lipase
   a. Exocrine pancreatic insufficiency (1) Chronic pancreatitis (2) Pancreatic carcinoma (3) Cystic fibrosis (4) Pancreatic resection
   b. Ulcerogenic tumor of the pancreas (Zollinger Ellison syndrome)

B. Reduced intestinal bile salt concentration

1. Liver disease
   a. Parenchymal liver disease b. Cholestases (intrahepatiac or extrahepatic)
2. Abnormal bacterial proliferation in the small bowel
   a. Afferent loop stasis b. Strictures c. Fistula d. Blind loops e. Multiple diverticula of the small bowel f. Hypomotility states (diabetes, scleroderma; intestinal pseu obstruction
3. Interrupted enterohepatic circulation of bile salts a. Ileal resection b. Ileal inflammatory disease (Crohn's regional ileitis)
4. Drug induced (by sequestration or precipitation of bile salts) a. Alcohol b. Cholestyramine c. Calcium carbonate d. Neomycin

C. Inadequate absorptive surface

1. Intestinal resection or bypass a. Mesenteric vascular disease with massive intestinal resection b. Crohn's regional enteritis with multiple resection c. Jejunoileal bypass
2. Gastroileostomy

D. Lymphatic obstruction

1. Intestinal lymphangiectasia Small intestine biopsy show severe distortion of the villous architecture with marked dilatation of the lamina propria lymphatics secondary to narrow or obstructive lymphatic channels. The cause may be idiopathic, or tuberculous enteritis, granulomatous enteritis, or lymphoma. Mild fat malabsorption of about 20 g/d, protein losing enteropathy & ascites may develop.
2. Whipple's Disease
3. Lymphoma4. Kohlmeier Degos (primary progressive arterial occlusive disease)

E. Cardiovascular disorders

1. Constrictive pericarditis
2. Congestive heart failure
3. Mesenteric vascular insufficiency
4. Collagen vascular disease with vasculitis

F. Endocrine & metabolic disorders

1. Diabetes mellitus
2. Hypoparathyroidism
3. Adrenal insufficiency
4. Hyperthyroidism
5. Zollinger sEllison syndrome of the pancreas
6. Carcinoid syndrome

G. Primary mucosal absorptive defects
1. Inflammatory or infiltrate disorders

• a. Regional enteritis
• b. Amyloidosis
• c. Scleroderma
• d. Lymphoma
• e. Eosinophilic enteritis.   Often with a history of urticaria, asthma, or other allergies. Sx of nause, abd. cramp, diarrhea may be related to ingestion of a particular food.Most pts have peripheral eosinophilia, hypoalbuminemia related to a protein losing enteropathy.Small intestine biopsy show chronic inflammation with a marked increase in eosinophili infiltration in the lamin propria. Small intestine x ray may reveal marked thickening of mucosal folds or even a mass lesion inthe gastric antrum or upper small intestine. Rx: If Sx persist for >5 7d, PO prednisone 20 30 mg/d should be given for 1-4 wks.
• f. Tropical sprue.    It is linked to infection of an undefined agent. Small intestine biopsy show partial flattening of intestinal villi & subepithelial lymphocytic infiltration.75% of pts respond within 2 weeks to folic acid 5 mg tid PO Rx for 1 week then 1 mg tid maintenance dose. 25% of pts however require antibiotic tetracycline 500 mg qid, or ampicillin 500 mg qid for 2 4 weeks or longer for remission.
• g. Infectious enteritis (hook worm, Giardia, salmonellosis, etc.) h. Mucosal lesion associated with intestinal bacterial growth i. AIDS (acquired immunodeficiency synd) Infectious agents can only identified in only 1/2 of the pts. Small intestine biopsy changes are similar to that seen in tropical sprue.
• h. Biochemical or genetic abnormalities
  1.  CELIAC SPRUE (nontropical sprue)
  2.  Abetaliproteiinemia
  3.  Hartnup disease
  4.  Cystinuria
  5.  Hypogammaglobulinemia