[GASTRO] MALABSOPRTION

Classification of Malabsorption

Classification of Malabsorption Syndromes

Disease of the Enterohepatic Circulation of Bile Acids

Pathophysiology of Clinical Signs of Malabsorption Disorder

Diseases that can be diagnosed by Small Intestine Mucosal Biopsies

Luminal digestion

initiated by lingual and gastric lipase and gastric pepsin, and continues in the small bowel by the actions of pancreatic enzymes and bile salts.

Small intestinal mucosal digestion and absorption

mediated by enterocyte brush border enzymes including disaccharidases, enterokinases, and peptidases, which digest nutrients upon contact, and by mixed micelles containing lipids and bile salts

Celiac Disease

>mediated by enterocyte brush border enzymes including disaccharidases, enterokinases, and peptidases, which digest nutrients upon contact, and by mixed micelles containing lipids and bile salts.
>autoantibodies to tissue transglutaminase

Tropical Sprue

manifested by chronic diarrhea, steatorrhea, weight loss, and nutritional deficiencies, including both folate and vitamin B12

Factors affecting absorption

1. Anatomic Length
2. Anatomic Structural Organization
3. Motility
4. Entry of Nutrients
5. Sites of absorption

Proximal Absoprtion

1. Fat
2. Sugar
3. Peptides and Amino acids
4. Iron
5. Folate
6. Calcium
7. Water and Electrolytes

Middle part/ Jejunum

1. Sugars
2. Peptides and Amino Acids
3. Calcium
4. Water and Electrolytes

Distal

1. Vit B12
2. Folate
3. Water and Electrolytes

Secretin Test

Test for Pancreatic Insufficiency
>Secretin- is a hormone that is produced by the upper duodenum. It stimulated the pancreas to release digestive enzymes.

Schilling Test

a diagnostic test for vitamin B12 deficiency

Lactulose and Glucose Hydrogen Breath Test

Test for bacterial overgrowth
>Lactulose is a sugar that is not absorbable. In the presence of bacteria, lactulose will be fragmented, causing it to be absorbed in the system and breath out in the respiratory system.

Few disorders that require Small Intestine Biopsy

1. Giardia
2. Crohn's disease
3. Celiac Disease
4. Whipple Disease

Sign and Symptoms of Malabsorption

1. Malnutrition
2. Weight Loss
3. Diarrhea

Thiamine Deficiency

Beriberi: neuropathy, muscle weakness and wasting,
cardiomegaly, edema, ophthalmoplegia, confabulation

Riboflavin deficiency

Magenta tongue, angular stomatitis, seborrhea, cheilosis,
ocular symptoms, corneal vascularization

Niacin deficiency

pellagra: dermatitis, diarrhea, dementia, death

Vitamin B6 deficiency

Scaly dermatitis, depression, confusion, convulsions, anemia, microcytic anemia

Folate deficiency

megaloblastic anemia, neural tube defects

Vitamin B12 deficiency

megaloblastic anemia

Vitamin C deficiency

scurvy, hemorrhagic diathesis, poor wound healing

Vitamin A deficiency

night blindness, xerophthalmia

Vitamin D deficiency

rickets, osteomalacia

Vitamin E deficiency

Peripheral Neuropathy, spinocerebellar ataxia, skeletal muscle atrophy, retinopathy

Vitamin K

Elevated prothrombin time, bleeding

Inadequate Digestion

1. Liver and Biliary Tract Disorders
a. Liver Cirrhosis
b. Biliary tract obstruction
c. Pancreatic insufficiency

>Liver produces bile acids > digestion and absorption of fats

2. Post Gatrectomy Malabsorption
-Decrease release of Cholestosytokinin and Secretin
-Inadequate micing biliopancreatic secretions with gastric content
-Loss of gastric reservoir function

Inadequate Absorptive surface short bowel syndrome

-Resection of <40-50% of SI is well tolerated, provided that the proximal duodenum, distal half of the ileum and ileocecal valve is spared
-You need to preserved >50%

Bacterial Overgrowth of SI

>The proximal SI is STERILE
1. acid milieu of the stomach
2. Intestinal Peristalsis - major role
3. Secretion of Ig (caproantibodies) into the lumen of SI

Pathophysiology of Bacterial SI

1. Bacterial deconjugation of bile salts
2. Bacterial production of toxins vs. enterokinases
3. Destruction of intestinal mucosa by bacterial toxins
4. Bacterial consumption of Vitamin B12

Chronic intestinal pseudo-obstruction

recurrent episodes of intestinal obstruction which all known cause of illness have been excluded
Decreased Motility > stasis > bacterial overgrowth

Scleroderma

-impaired intestinal motility and presence of jejunal pseudodiverticulosis
-Involvement of the intestinal wall itself

Malabsorption in AIDS

-Enteric infections
-Small intestinal Kaposi's Sarcoma

Treatment for Whipple's disease

Trimethoprim Sulfamethoxazole x 1yr

Intestinal Lymphoma

-Resembles Celiac sprue
-Incomplete response to gluten free diet
-Abdominal pain and fever
-Steatorrhea
-Intestinal obstruction
-Hepatosplenomegaly

Diagnosis of Lymphatic Obstruction

-Small bowel Biopsy : total absence of villi or lesser degrees of blunting and shortening of villi.
-Lamina Propia is massively infiltrated by lymphoid cells.

Lymphatic obstruction

1. Whipple's Disease
2. Intestinal Lymphoma

Defects in Mucosal Structure and Function

1. Inflammatory Bowel Disease
2. Biochemical or Genetic abnormalities : Celiac Sprue