C - Enzymes & Cardiac Biomarkers Flashcards
define enzyme
substance (usually a protein that increases the rate of a chemical reaction without itself being changed in the process
what is Km (michaelis menten constant)
substrate concentration at which reaction velocity is 50% of maximum
what does having a high Km mean
weak binding
what does having a low Km mean
strong binding
when are intracellular enzymes released
- give examples of this
tissue / cellular injury
- infection, immune mediated, inflam, MI, inherited, trauma, toxins, tumour
where is ALP found
bone
biliary system
tumour marker - testicular etc
placenta
intestine
what does a lack of ALP cause
osteomalacia
when is ALP found in trimester
last trimester
when is ALP release from bone physiological
childhood as bones grow
raised ALP. Dx?
LFTs - gamma GGT or ALT
vitamin D
why check vit D with raised ALP
low vit D can cause raised ALP
why is ALP high in kids
bone growth releases ALP
where is ALT predominantly found
liver
where is AST predominantly found
heart, liver, muscle, kidney
why is AST not used for heart / kidney / muscle then but is used for liver?
heart - use trop
kidney - use creatinine or eGFR
muscle - use CK
liver - only AST and ALT are really useful
common causes of high ALT
hepatic - toxins, hepatitis, NAFLD, cancer, ischaemia
kidney issues
pancreatitis
MI
best biomarker for pancreatitis
amylase
when can you get hepatic ischaemia
post MI
upper limit of ALT
45
what happens to ALP when you fast
drops down low
where is gamma GGT released from
hepatobiliary system
pancreas
kidney
is GGT useful at distinguishing between hepatic and biliary issues?
no - high in both
what marker is useful in distinguishing between hepatic and biliary issues
ALT:ALP ratio
when is high GGT released due to high levels intracellularly that get released during normal cell turnover
alcoholics
