WEEK 7: Liver function and testing Flashcards
liver processes
waster management and treatment
recycling
production and storage of essential molecules
what does the liver store glucose as?
glycogen
what is the main reason why the liver is the preferred organ to house the majority of detoxification processes?
to protect the body against what you eat.
the majority of toxins are absorbed through the intestines.
tests to detect abnormalities in liver function
indirect measures
measurement of enzymatic activty that has leaked into plasma due to hepatocellular damage (ALT and AST)
alkaline phosphatase
indirect measures to detect liver abnormalities
total bilirubin levels in blood and urine
total protein and albumin levels in plasma
prothrombin time
how is bilirubin measured?
direct bili - primarily conjugated bili
indirect bili - unconjugated bili
total - sum of both above
direct measured - all water soluble bili
total - boths forms solubilized by an accelerator
indirect- total-direct
what bilirubin is found in the urine?
unconjugated only
method to measure bilirubin in serum
form azidopyroles by adding diazonium salt to sample.
add ascorbic acid to stop the reaction.
Add alkaline tartrate to produce the blue-coloured form of azidopyroles.
Measure absorbance at 600nm
method to measure bilirubin in urine
same as in serum but different diazonium salt.
Must be fresh urine.
what does the measurement of total protein of biological fluids include?
serum, urine, cerebral spinal fluid
explain the method of the biuret test to measure total protein.
- under alkaline conditions
- cupric ions (Cu2+) react with proteins with at least 2 peptide bonds
- reagent contains Na+/K+ tartrate to form a complex with the Cu2+ ions and maintain their solubility in alkaline solution
- the absorbance of Cu+ - protein complex at 540nm is directly proportional to the concentration of the protein in the sample
conditions for the measurement of total proteins
serum or plasma - serum is preferred
haemolysis should be avoided
functions of albumin
maintainence of osmotic pressure in vascular and extravascular spaces
transport a larger number of compounds including free fatty acids, ions, hormones, drugs, bilirubin
how is albumin measured?
automated dye-binding methods which use bromocresol green dyes with great affinity for albumin.
Then is measured at 628 nm which is proportional to the albumin concentration in sample
what is fetoprotein? what can detection in adults mean?
fetal albumin - normally undetectable after infancy but elevated levels in males and non-pregnant females may indicate tumours
non-laboratory test of the liver
ultrasound
liver biopsy
what could cause impaired bile secretion?
cystic fibrosis
inflammation
toxins
hormones
what could obstruct bile flow?
primary biliary cirrhosis
gallstones
tumours
how is jaundice cause? what are the characteristics?
abnormal metabolism or retention of bilirubin
brownish-yellow pigmentation of the skin, sclera and mucous membranes
what is Gilbert’s syndrome
decreased conjugation activity in the liver due to faulty gene
what is unconjugated hyperbilirubinemia?
excess production of bilirubin exceeds capacity of liver to remove and conjugate the pigment.
More bilirubin is excreted in bile and urinary urobilinogen is increased
what is conjugated hyperbilirubinemia?
leakage of bilirubin from liver cells or the biliary system into the bloodstream or normal route of excretion is blocked.
Water-soluble conjugated bilirubin entering the systemic circulation is excreted in urine - deep orange-brown colour.
if there is complete biliary obstruction, no bilirubin reaches the gut, no urobilirubin is formed and stools are pale in colour.
go through types of jaundice
what is ALT?
alanine aminotransferase
it converts l-alanine to pyruvate
what is AST?
