Chemical Pathology - Enzymes + Cardiac Markers Flashcards
What condition causes high serum levels of amylase (~>10x upper limit)?
Acute pancreatitis
What are some non-specific causes of a raised serum amylase?
- Renal insufficiency
- Intestinal infarct/peritonitis
- Cholecystitis
- Salpingitis
- Ectopic pregnancy
- Abdominal cancers
What condition is highly indicative if it’s >3x the upper limit of lipase?
Acute pancreatitis
Which is more specific in diagnosing acute pancreatitis, amylase or lipase?
Lipase
What conditions can see a raised lipase?
- Renal linsufficiency
- Small intestinal ischaemia/obstruction
- Sepsis
- DKA
- Cholecystitis
What is the most widley used marker of muscle damage?
Creatine Kinase
What Creatine Kinase markers are there and what high levels indicate?
CK-MM = skeletal muscle
CK-MB (1+2) = Cardiac muscle (re-infarcts)
What are physiological causes of a raised creatine kinase?
Afro-caribbean (<5x upper normal limit)
What are some pathological causes of a raised creatine kinase?
- Duchenne Muscular Dystrophy (>10x ULN)
- MI (>10x ULN)
- Rhabdomyolysis
- Statin-related myopathy
What urine sign is seen in rhabdomyolysis?
Tea-stained urine
What marker is good at detecting re-infarcts?
Myoglobin
What is statin-related myopathy and some RFs?
- Spectrum of myalgia to rhabdomyolisis secondary to taking statins
RFs:
- High dose
- Genetic predisposition
- Prev. Hx of myopathy with another statin
Reversible increase in CK
Where is Alkaline Phosphatase present in high concentrations?
- Liver
- Bone
- Intestine
- Placenta
How can you differentiate between liver + bone ALP?
- Rise in GGT (liver)
- Electrophoresis
- Bone-specific assay of ALP
What are some physiological causes of a raised ALP?
- Pregnancy (3rd trimester)
- Childhood (during growth spurts)
What are some pathological causes of a raised ALP?
> 5x ULN:
- Bone: Paget’s, Osteomalacia
- Liver: Cholestasis, Cirrhosis, Obstructive Jaundice
<5x ULN:
- Bone: Tumours, Fractures, Osteomyelitis
- Liver: Infiltrative Diseases, Hepatitis
When is Brain natriuretic peptide raised?
Heart Failure (>400 = highly sensitive, <100 = exclude)
What is brain natriuretic peptide?
- A hormone that is primarily released from the ventricles in the heart
- Released in response to ventricular stretch
- Roles in reducing systemic vasoconstriction, sodium retention + renal sympathetic activity
What is a confounding factor to interpretation of a raised brain natriuretic peptide?
CKD
What are some pros to NT-proBNP?
- More sensitive than BNP
- Greater prognostic value
What is troponin?
NOT AN ENZYME
- Myocardial injury marker
- Protein which forms part of the contractile apparatus in cardiomyocytes, released during an MI
When is troponin measured?
6 + 12 hours post-onset of pain
- 100% sen + 98% spe at 12-24hrs
How long does troponin remain elevated for?
3-10 days
What conditions (aside from MI) see a raised troponin?
- Coronary spasm
- Coronary dissection
- PCI
- Myocarditis
- PE
- HF
- Cardiomyopathies
- Sepsis
- Cardiac surgery
- Chest trauma
- Defibrillation
What is an international unit?
- 1 international unit is the quantity of enzyme that catalyses 1uMol of substrate in a minute (at given temperature + pH)
- Measure of enzyme activity (not mass or concentration)
