Chemical Pathology 15 - Enzymes and cardiac markers Flashcards
(32 cards)
What is the Km?
Michaelis Mentin constant
= concentration of substrate at which the reaction velocity is 50% of maximum
What tumour marker can be used for germ cell, ovarian and testicular malignancies?
AFP
When is ALP elevated physiologically?
In pregnancy and childhood
Recall 4 pathologies that can cause a raised ALP
How to distinguish between the diff sources of ALP?
- Bile duct pathology (eg cholestatic liver disease)
- Bone pathology (fracture/ metabolic bone disease)
- Germ cell tumours
- Intestinal pathology (but not routinely used for investigation of bowel disorders)
*To distinguish between the diff sources: can order bone specific ALP assay; OR can order gamma GT- which would rise in the case of liver source of ALP*
Which LFT enzyme is most specific to liver pathology?
ALT
How can hepatic and biliary disease be best distinguished on the LFTs?
ALT:ALP ratio
If ALT much higher than ALP = hepatic
How many isoenzymes of LDH exist?
5
Recall 3 things that a raised LDH may indicate
- Haemolytic anaemia
- Tumour marker (lymphoma, germ cell testicular Ca)
- Myositis (rheum)
Which enzyme is markedly raised in acute pancreatitis?
Serum amylase
What is the most likely cause of a raised CK-MB1?
Rhabdomyolysis (history of long lie/ big fall?)
Where is CK-MB1 vs CK-MB2 produced?
CK-MB1 - skeletal muscle
CK-MB2 - cardiac muscle
**you only have one heart but several muscles - but it’s actually the opposite of this!
In which population is CK physiologically slightly raised?
Afrocaribbean
Which prescription drug may be the cause of a raised CK-MB1?
Statins (as they can cause myopathy)
When does troponin I peak following chest pain?
2-4 hours
Within what time period does troponin I return to normal following a cardiac event?
5-10 days
**this means it is not a good marker of re-infarction
What change in troponin levels is indicative of cardiac myocyte injury?
A 50% increase or decrease between 2 measurements
When is amylase level high?
Usually after acute pancreatitis
*usually 10x the upper limit of normal*
What other nonspecific conditions can cause a ise in amylase?
renal insufficiency
intestinal infract/peirtonitis
cholecytsitis
salpingitis
ectopic pregnancy
What does lipase >3 upper reference range indicate?
acute pancreatitis
Which is the most specific marker of acute pancreatitis?
Serum LIPASE
What is creatine kinase a marker of?
Muscle damage
What are the two types of creatine kinase?
CK-MM: skeletal muscle
CK-MB (1 and 2): cardiac muscle
What causes high creatine kinase?
Physiological: Afro-Caribbean (<5x upper limit of normal)
• Pathological: Duchenne Muscular Dystrophy (>10xULN), MI (>10xULN), Rhabdomyolysis,
Statin related myopathy (spectrum of myalgia to rhabdomyolysis occurring secondary to taking statins. RF: high dose, genetic predisposition, previous history of myopathy with another statin. Causes rise in CK. Reversible with cessation of statin).
What is BNP?
