WEEK 7: Liver function and testing

Question 1

liver processes

Answer 1

waster management and treatment
recycling
production and storage of essential molecules

Question 2

what does the liver store glucose as?

Answer 2

glycogen

Question 3

what is the main reason why the liver is the preferred organ to house the majority of detoxification processes?

Answer 3

to protect the body against what you eat.
the majority of toxins are absorbed through the intestines.

Question 4

tests to detect abnormalities in liver function

Answer 4

indirect measures
measurement of enzymatic activty that has leaked into plasma due to hepatocellular damage (ALT and AST)
alkaline phosphatase

Question 5

indirect measures to detect liver abnormalities

Answer 5

total bilirubin levels in blood and urine
total protein and albumin levels in plasma
prothrombin time

Question 6

how is bilirubin measured?

Answer 6

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

Question 7

what bilirubin is found in the urine?

Answer 7

unconjugated only

Question 8

method to measure bilirubin in serum

Answer 8

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

Question 9

method to measure bilirubin in urine

Answer 9

same as in serum but different diazonium salt.
Must be fresh urine.

Question 10

what does the measurement of total protein of biological fluids include?

Answer 10

serum, urine, cerebral spinal fluid

Question 11

explain the method of the biuret test to measure total protein.

Answer 11

• 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

Question 12

conditions for the measurement of total proteins

Answer 12

serum or plasma - serum is preferred
haemolysis should be avoided

Question 13

functions of albumin

Answer 13

maintainence of osmotic pressure in vascular and extravascular spaces
transport a larger number of compounds including free fatty acids, ions, hormones, drugs, bilirubin

Question 14

how is albumin measured?

Answer 14

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

Question 15

what is fetoprotein? what can detection in adults mean?

Answer 15

fetal albumin - normally undetectable after infancy but elevated levels in males and non-pregnant females may indicate tumours

Question 16

non-laboratory test of the liver

Answer 16

ultrasound
liver biopsy

Question 17

what could cause impaired bile secretion?

Answer 17

cystic fibrosis
inflammation
toxins
hormones

Question 18

what could obstruct bile flow?

Answer 18

primary biliary cirrhosis
gallstones
tumours

Question 19

how is jaundice cause? what are the characteristics?

Answer 19

abnormal metabolism or retention of bilirubin
brownish-yellow pigmentation of the skin, sclera and mucous membranes

Question 20

what is Gilbert’s syndrome

Answer 20

decreased conjugation activity in the liver due to faulty gene

Question 21

what is unconjugated hyperbilirubinemia?

Answer 21

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

Question 22

what is conjugated hyperbilirubinemia?

Answer 22

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.

Question 23

go through types of jaundice

Question 24

what is ALT?

Answer 24

alanine aminotransferase
it converts l-alanine to pyruvate

Question 25

what is AST?