GI Lab Assessment Flashcards
Changes in the CBC; what might each of the following indicate in regards to GI?
- anemia
- neutropenia
- thrombocytopenia
What is the MC cause of pancytopenia?
anemia: depends on etiology of liver dz.
- Liver dz d/t alcoholism:
- -GI blood loss
- -nurtitional deficiency
- -alcohol as direct toxin
neutropenia: sequestering WBC in the spleen b/c of portal htn d/t hepatic cirrhosis (alcoholism)
thrombocytopenia:
sequestering in the spleen b/c of portal htn d/t hepatic cirrhosis (alcoholism)
**Having all three of these deficiencies = pancytopenia
MC cause of pancytopenia = alcoholism
WHat are the types of anemia?
- microcytic
- macrocytic
Microcytic:
- Fe deficiency
- Thalassemia
- Anemia of chronic dz
- Lead toxicity
Macrocytic:
- Folate deficiency
- Vit B12 deficiency
- Myelodysplastic syndrome
- Liver dz (ETOH)
LFT’s:
-Pros and Cons
Pros:
- provide noninvasive method to screen for presence of liver dz
- measure the efficacy of tx for liver dz
- used to monitor progression of liver dz
- can reflect severity of liver dz
Cons:
- most do not accurately reflect how well the liver is functioning
- abnormal values CAN be cause by dz unrelated to the liver.
- test may be normal in pts who have advanced liver dz
Tests that reflect injury to hepatocytes?
WHat is normal value of these enzymes?
Highest elevations of these enzymes correlate with what dzs?
Alanine Aminotransferase (ALT)
Aspartate aminotransferase (AST) *these enzymes are normally intracellular, they are only released into the blood stream when hepatocytes are injured.
Normal value is less than 30-40 unit/L each.
Highest elevations of ALT and AST = viral hepatitis, ischemic hepatitis, toxicity (esp tylenol)
Rapid decline in aminotransferases is usually a sign of recovery, T/F?
True, BUT it may reflect massive destruction of viable hepatocytes signaling acute liver failure.
What is cholestasis?
Liver tests that reflect cholestasis? What is the value of this test?
What is a non-GI cause of an elevated test (the one from the previous question).
Cholestasis = any condition in which the flow of bile from the liver stops or slows.
Liver Tests:
- alkaline phosphatase: MAJOR value of finding an elevated ALP in dx of liver dz is recognition of cholestatic dz.
ex. gallstone; ALP gets backed up and goes into serum.
non-GI cause of elevated ALP is metastatic bone cancer.
If ALP is elevated what to two test do you do next to determine the source of ALP? Explain each.
5’- Nucleotidase: an increase in a NON-PREGNANT pt with an increase in ALP SUGGESTS the increase in ALP is from the LIVER.
Gamma-glutamyl Liver Enzyme: when GGT and ALP are both elevated you can confirm the liver is source of dz.
*may also see elevation in acute liver toxicity such as after an alcohol binge.
Hepatobiliary dz will have an increase in conjugated or un-conjugated bilirubin?
increased production or decreased excretion can cause increased levels of conjugated or unconjugated bilirubin?
When is UA urobilinogen positive?
Hepatobiliary dz ( meaning obstructive or hepatocellular damage) will have an increase in CONJUGATED bilirubin.
Increased production or decreased excretion can cause increased levels of unconjugated bilirubin
UA urobilinogen is positive when direct bilirubin is excreted via the kidneys.
What are 4 causes of both conjugated and unconjugated elevations in bilirubin?
- biliary obstruction
- intrahepatic cholestasis
- hepatocellular injury
- hepatocellular defects of canalicular excretion or sinusoidal re-uptake.
Elevated ammonia levels may cause what?
WHat causes elevated ammonia levels in the blood with respect to the GI tract?
What is the most accurate method to determine an ammonia level? What are some factors that may result in inaccurate results?
-hepatic encephalopathy; this is reversible impairment of neuropsychiatric function w/ impaired hepatic function and increased ammonia concentrations.
LIVER DAMAGE. Ammonia is produced by catabolism of colonic bacteria, when there is liver damage the liver cannot clear the ammonia like it normally does.
Most accurate method to determine ammonia is drawing an arterial ammonia level.
Factors that can result in inaccurate results:
- fist clenching
- use of tourniguet
- whether the sample was put on ice or not.
Are follow up ammonia levels a good idea? why or why not?
Yes, following the ammonia level is necessary to knowif the tx aimed at helping the liver is successful in lowering the ammonia level.
Albumin:
- serum level reflects?
- synthesized where?
- hypoalbuminemia can reflect disorders such as?
serum level reflects:
- rate of synthesis
- rate of degradation
- volume of distribution
Synthesized in the liver
Hypoalbuminemia can reflect disorders such as:
- systemic inflammation
- malnutrition
- when present with CHRONIC LIVER DZ it reflects the SEVERITY of the liver dz.
PT:
- tests what?
- PT is usually measured in place of what?
tests the time it takes for clot formation, indirectly testing the clotting factors made by the liver..
PT is usually measured in place of the individual clotting factors.
In the presence of liver dz what would you expect the PT and albumin test to reveal?
in the presence of liver dz you would expect the PT to be increased and albumin levels to decrease, thereby directly measuring liver function.
clotting factors & albumin produced in liver, if liver is failing neither will be produced.
Amylase & Lipase
-secreted from where?
- the level of elevation does or does not correlate with the level of damage to the pancreas?
- in acute pancreatitis which stays elevated longer?
- are follow up tests of lipase and amylase a good idea? why or why not?
secreted from the pancreas
the level of elevation DOES NOT correlate with the level of damage to the pancreas.
In acute pancreatitis Lipase remains elevated longer so it is thought to be more accurate.
Follow up tests are not needed, the enzymes may fluctuate in both directions while the pt remains sick.
