role of clinical biochemistry in liver disease Flashcards
what are the transanimase enzymes
ALT and AST
transanimase activities in human tissues
AST highest in heart and liver, lowest in serum and RBCs
ALT highest in lover and lowest in lungs, RBCs and Serum
both med in kidney, muscle, pancreas
factors influencing serum transanimase finding
based on 3 factors
extent of damage to tissue releasing them
amount of each transanimase in that tissue
rate of clear eve of enzyme from circulation
ALT half life is 47h and AST 17h
complication - hepatic gets have two forms of AST, cytosol and mt
how does ALT vary with BMI
mean ALT inc with inc BMI
consideration for interpreting transanimases
biological variables - diurnal, dietary factors eg coffee, race (higher if african or hispanic), weight
ref range selection - pop exclusion criteria (more rigorous, lower the ref range, skewed fist curve)
drugs - prescribed and OTC
distribution of transanimase curve
tails off to higher end
not even
what is ALP
alkaline phosphatase
catalysed the hydrolysis of phosphate monoesters
membrane bound, liver and bone
found in cells next to canalculi
unregulated in response to bile duct obstruction and infiltrative/space occupying lesions in liver
what is GGT
mainly found in hepatobiliary system inc in blood conc due to inc synthesis by alcohol/ drugs (anti convulsants) billary obstruction liver tumours small inc with hepatitis
tissues containing ALP and GGT
ALP
hepatocytes, billary tract, bone, kidney, intestinal mucosa, pancreas, placenta
GGT
hepatocytes, billary tract, kidney, pancreas
can both be induced by drugs/alcohol
some tumours have placental ALP
ALP isozyme pattern sometimes req
protein synthesis routine tests for liver
serum albumin conc
prothrombin time - INR
removal of potentially toxic substances - drugs and bilirubin
production of bilirubin from haem
80% of bilirubin from RBCs taken up by RE system for degradation
haem oxygenate release iron from haem molecule to form biliverdin reductase
tightly bound to albumin
where does bilirubin go
unconjugated bilirubin + albumin in blood
to liver, conjugated to glucuronic acid
to conjugated bilirubin to biliary sytem
bacterial proteases form urobillogen to faeces in SI
Or via kidneys
how can bilirubin levels be measured
total - conjugated and unconjugated
conjugated- 40%, water soluble, excreted in bile, is raised dark urine
unconjugated - not water soluble, bound to albumin so doesn’t appear in urine
how does liver disease present
jaundice - with or with our itching
pain - constant or colicky
non specific - nausea, fatigue, weight loss
incidental
detected at serum bilirubin conc of 50 umol/l, obvious at 100
diagnoses of liver disease
clinical presentation
pattern of routine liver tests
more specific tests, inc diagnostic radiology
