Enzymes and Cardiac Markers Flashcards
What are enzymes primarily used to determine?
Diseases that result in abnormalities of enzyme concentrations /function
Tissue da mage
Where are enzymes usually found
Intracellularly
may be cytoplasmic / sub cellular (in organelles)
What occurs as necrosis becomes more severe?
You go from just cytoplasmic enzymes being released
To intro-organellar enzymes also being released
What organs is All Phosph found in?
Liver
bone
intestine
placenta
How does ALP change with age?
High in newborn
Second spike at puberty
What organs are pathological increases in ALP due to ?
Bone
Liver
When is ALP increased in osteoporosis?
ONLY if there is a fracture
Otherwise normal
What enzyme should you measure if suspecting liver disease in a patient with high ALP?
GGT
What method do you use to separate out ALP isoenzymes?
Electrophoresis
What are physiological causes of ALP rise?
Pregnancy (third trimester, from placenta)
Childhood (growth spurt)
What are pathological causes of ALP?
MORE THAN x5 normal
- bone : Paget’s disease, osteomalacia
- liver: cholestasis, cirrhosis
LESS THAN x5 normal
- Bone: tumours, fractures, osteomyelitis
- Liver: infiltrative disease, hepatitis
What organ is ALT mainly found in?
The LIVER
But not very sensitive (also present in other organs like kidney, pancreas)
When is GGT raised?
Hepatic or biliary disease
What drugs up regulate GGT
alcohol
rifampicin
phenytoin
What is LDH a good marker for?
Tumours (lymphoma, seminoma)
Haemolysis, myositis
How much is amylase raised by in acute pancreatitis?
x10
What other organ produces amylase?
salivary glands
What is creatine kinase a general marker of?
Muscle damage
what are the three forms of CK?
MM - skeletal muscle
MB - cardiac muscle
BB - brain
What is a side effect of statins in terms of raised markers=
Raised CK
What causes raised CK in statin patients?
Myalgia, rhabdomyolysis
What are risk factors to statin related myopathy?
Polypharmacy (esp other drugs metabolised by CYP3A4)
High dose
Genetic
Previous history of myopathy with another statin
Vitamin D deficiency
What are other causes of raised CK other than statins?
Muscle damage from any cause Myopathy e.g. Duchenne muscular dystrophy MI severe exercise Physiological
What are 3 old fashioned enzymes for MI monitoring, and what is the order in which they rise?
CK > AST > LDH
What is the main marker now used to identify MI?
Troponin
What is the first enzyme to rise in MI? why?
Myoglobin
Because it is loose in the cytoplasm
Why are there two peaks of troponin?
FIRST PEAK due to free cytosolic pool of troponin
Second peak due to breakdown of troponin in the contractile apparatus
When does troponin rise after MI?
4-6h post MI
When does Troponin peak after MI?
12-24h
How long does troponin remain elevated after MI?
3-10 days
When should troponin be measured after an MI?
at 6 h
at 12 h after onset of chest pain
What are biomarkers of cardiac failure?
ANP - atria
BNP - ventricles
HIGH SPECIFICITY (if negative, confirm NO HF)
What is unit of enzyme activity?
Unit/Litre
what levels of BNP let you include / exclude cardiac failure
<100: exclude
>400: include
which cardiac marker is NOT an enzyme
TROPONIN
