Malabsorption- Clinical and Path Flashcards
Malabsorption may be generalized or it may be a very specific type of malabosorption. Pay especially close attention to fat because the absorption of fat is very complex.
ok
Steattorhea definition
Greater than 5% of dietary fat in stool
Whom to suspect of having steatorrhea?
- weight loss
- stool characteristic
- osteomalacia– vitamin D is fat soluble vitamin
- Easy bruising- vitamin K (ADEK)
- iron deficiency anemia not due to blood loss
- Adult development of lactase insufficiency
- Gastric surgery- billroth II…take out the antrum of the stomach where gastrin is produced which leads to less acid.
Steattorhea stool characteristic
floats greasy stinks oil droplets hard to flush
Mechanisms causing diarrhea in steattorhea?
- More osmotically active substances in the GI lumen from malabsorption pulls out water.
- Hydroxylation of 10- hydroxy oleate acts as a cathartic ( something that speeds up defecation)
- Fatty Acids themselves impair fluid and electrolyte absorption
What is chemical fat balance?
How much fat you are eating and how much fat you have in your stool
What is D-xylose
Xylose is a pentose sugar that doesn’t require dgestion to be absorbed, very unique. D-xylose test allows you to differentiate between a digestion problem and an absorption problem. If someone has a digestion problem, they should still absorb D-Xylose without any trouble. If there is an absorption problem, they will not
Secretin test?
Most sensitive test for pancreatitis. Give secretin which stimulates bicarb production by the pancreas and then measure bicard secretion. if the pancreas is injured, no bicarb. Very hard to do.
x-ray
with all of these tests you are looking to see whether it is a digestion problem or an absorption problem. Chronic pancreatitis will often show calcifications on x-ray.
Hydrogen breath test?
Carbohydrate malabsorption. If carbs are not absorbed, bacteria will ferment the carbs and release Hydrogen
What causes the most steatthorea?
Pancreatic insufficiency
What is zollinger-Ellison
Gastrin producing tumor…tons of acid….this acid gets in the small intestine and prevents the pancreatic enzymes from working and thus you get malabsorption
Conditions that can cause bile acid insufficiency will cause steattorhea. SOme examples are
- Cholestatic liver disease
- Terminal Illuem resection- no reabsorption of bile acid.
- Bacterial overgrowth in small intestine- conjugates bile acid and prevents it from working correctly
- Reduced CCK release-
Issues with intestinal stage absorption deal with epithelial cell surface digestion
ok
Remember that problems with lymphatic transport will also impede fat absorption
ok
Characteristic pathologic finding of malabsorption
Villous Blunting
Intraepithelial lymphocytes (CD-8)
Celiac disease
Viral gastroenteritis can cause a temporary disacharidase (lactase) deficiency which can present as diarrhea upon ingestion of milk for a few days after the infection has cleared
ok
Infection in intestines, mesenteric lymph nodes, brain, heart, and joints?
Whipple Disease
LICCJ Lymph nodes Intestines Cerebral Cardiac Joints
WHipple disease causative organism is
Tropheryma WHippelii
Genetic predisposition to Celiac Disease?
95% have HLA- DQ2
What causes the most steatorrhea?
Pancreatic Insufficiency (loss of pancreatic lipase)
Intraluminal causes of malabsorption
- Chronic Pancreatitis
- Zollinger Ellison Gastrinoma
- Post Gastrectomy
- Cystic Fibrosis
- Also Bile Acid insufficiency (bile acids necessary for fat absorption) Things that can cause bile acid insufficiency= Cholestatic Liver disease, Terminal Illeum resection, Bacterial overgrowth in the small intestine (these little fuckers conjugate the bile acids and make them inactive, reduced CCK release means less bile released from gall bladder.)
Causes of malabsorption in GSE?
- Cells at the surface of intestine are immature
- Intestine is in a secretiry state
- Concentration of bile salts is reduced
- The abosrptive functions of mature enterocytes is reduced
- Complex lipid synthesis is reduced
- The endocrine cells that make CCK are reduced
- The absorptive area of the intestineis greatly reduced
What kind of antibody test is most helpful in GSE determination
IgA High sensitivity and specificity
Main manifestation of malabsorption=
Steatorrhea…this is the easiest to see, doesn’t mean that fat is the only thing being screwed with
