enzymes Flashcards
The Miachaelis-Menten constant = concenetration of a substarte at which the reaction velocity is 50% of the maximum
When is ALP found
Bone - fracture, Page’ts, osteomalacia, rickets, HPT, renal osteodystrophy
Intrahepatic / extrahepatic bile ducts -
Intestine - bowel disorders
When is raised ALP physiologically normal?
During pregnancy - released from placenta
or children
Clinical approach to ALP
Check LFTs - if normal, check vit D
Body breaks down bone to release phosphate, hence ALP is released
ALT vs AST - where do they come from?
AST can come from heart, liver, muscle, kidney, whereas ALT comes mainly from the liver
However there are better biomarkers for the other organs so we used these other ones
ALT raise meaning
Toxins - hepatocyte injury - alcohol, paracetamol overdose
Liver ischemia after heart attack
Hepatitis
and some other things - see
How can you test for intestinal ALP
Fasting ALP - if it returns to normal after being high, it suggests it’s coming from the intestines
Where is gamma glutamyl transferase released?
Liver/biliary system
Rifampicin
LDH can be raised due to
Lymphoma
Haemolysis
Germ cell testicular cancer - poor prognosis if LDH is high
Myositis
Hepatic disease
Serum amylase
in exocrine glands
If high - pancreatitis; only high in acute
perforated duodenal ulcer
bowel obstruction secondary to
Salivary gland - stones, infection
Macroamylase - immunoglobulin binds to amylase and makes renal excretion difficult - request amylase isoenzymes
Does serum amylase cause
measure calclium, glucose, lactate
CK due to
Skeletal muscle- rhabdomyolysis, myositis, polymyositis, severe exercise, myopathy
can cause acute tubular necrosis due to getting stuck in kidneys
???
What do we measure troponin for?
Cardiac specific troponin-I; injury to cardiac myocyte
primary - heart attack, myocarditis, cardiomyopathy, aortic dissection
Secondary cardiac injury
CK-MB
Is a specific isoform of CK-MB
rises within 2 hours
peaks at 12 hours
male <35ng/L
female <16ng/L
returns to normal 5-10 days later
What change in troponin means ACS
50 percent increase or decrease is suggestive of cardiac myocyte injury due to ACS
Narrowing of coronary arteries due to an atherosclerotic plaque can result in
STEMI
NSTEMI
Unstable angina
Stable angina
Cardiac chest pain + STEMI management
PCI
STEMI - subendocardial layer and myocardium
NSTEMI
Subendocardial layer
do serial troponins and check ref range, or if there is more than a 50% change in results
VT + VF = complications so do serial ECGs too
Unstable angina
BNP and NT=proBNP
Explain
cardiomyocyte stretch - BNP transcribed within 1 hr, caues you to PEEEEE to offload extra volume
We measure NT-proBNP, produced in equamolar amounts
NT-proBNP is stable for longer so can be measured 7 hrs down the line
Which drug gives you false BNP readings? What do you measure instead?
Entresto -
When might you measure BNP? If it’s high, what do you do next?
E.g. if a pt comes in with shortness of breath for heart failure
If it’s high, what do you do next? echocardiogram
what’s high in chronic pancreatitis?
Faecal elastase
