Biomarkers Flashcards
What is the rate limiting enzyme in haem synthesis?
ALA synthase (Aminolevulinic acid synthase)
Which enzyme deficiency causes urate overproduction and what condition is it associated with?
HGPRT deficiency
-> Lesh-Nyhan syndrome (self mutiliation, choreiform movements, mental retardation, gout)
Which enzyme marker is raised in Rhabdomyolysis?
CK-MM (creatinine kinase muscle type)
What is amyloid AA associated with?
Chronic inflammation (e.g., rheumatoid arthritis [RA], inflammatory bowel disease [IBD])
Amyloid AL is linked to which condition?
Myeloma amyloidosis
Which enzyme marker is raised in a non-smoker with cirrhosis?
Alpha-1 antitrypsin (A1AT) deficiency
Which enzyme marker is raised in someone with mumps?
Amylase (associated with parotitis)
Which enzyme marker is used to detect gastrointestinal cancers?
Carcinoembryonic antigen (CEA)
What is the order of rise of cardiac markers after a myocardial infarction? (5)
- Myoglobin
- Troponin
- Creatine kinase-myocardial 4. band (CKMB)
- Aspartate transaminase (AST)
- Lactate dehydrogenase (LDH)
What are the characteristics of myoglobin as a cardiac marker?
Rises first but is not specific to cardiac muscle
Peaks at 4-6 hours and declines within 24 hours
What are the key features of troponin as a cardiac marker? (3)
Most sensitive marker of myocardial infarction (not an enzyme)
Rises 4-6 hours post-myocardial infarction, peaks at 12-24 hours
Remains high for 3-10 days
What are the features of creatine kinase-myocardial band (CKMB) as a cardiac marker? (2)
Rises after 6 hours of chest pain onset
Peaks at 12-24 hours and declines within 48 hours
Where is alkaline phosphatase produced? (BLIP)
Liver, bone, placenta, intestines
What are the causes of raised alkaline phosphatase? (4) (in bone, liver, pregnancy, childhood)
Bone: Paget’s disease, osteomalacia, tumors, fractures
Liver: Cholestasis, cirrhosis, infiltrative diseases, hepatitis
Pregnancy (3rd trimester)
Childhood (during growth spurts)
What are the types of creatine kinase and their locations? (3)
Creatine kinase-muscle type (CK-MM): Muscle (95% of CK in plasma)
Creatine kinase-myocardial band (CK-MB): Heart
Creatine kinase-brain band (CK-BB): Brain (very low levels in plasma)
What are the causes of raised creatine kinase? (5)
Muscle damage (e.g., rhabdomyolysis, trauma)
Statin-related myopathy
Duchenne muscular dystrophy (DMD)
Myocardial infarction (MI)
Excessive exercise
What is found in very high levels in acute pancreatitis?
Amylase (needs to be 3x upper limit to be diagnostic)
Typically will be 10x high(higher than any other cause of high amylase)
When is amylase raised? (6)
Renal insufficiency
Intestinal infarct/ peritonitis
Cholecystitis
Salpingitis
Ectopic pregnancy
Abdominal cancers
What serum enzyme is 3x upper limit and specific to acute pancreatits?
Lipase (most specific than amylase)
Tends to be 3x higher, not 10x higher like amylase
What is brain natriuretic peptide (BNP)? (3)
Hormone primarily released from the ventricles in the heart.
Released in response to ventricular stretch and reduces systemic vasoconstriction, sodium retention, and renal sympathetic activity.
Levels of <100 are highly specific for excluding heart failure, while levels >400 are highly sensitive for heart failure.
Where is BNP released from?
The ventricles of the heart, in response to stretch
What to levels of BNP indicate?
Low levels <100 : highly specific to EXCLUDE heart failure
High levels >400 : highly sensitive for heart failure
What does BNP do systemically?
reduces systemic vasoconstriction, sodium retention, and renal sympathetic activity.
What is a key confounding factor in the interpretation of BNP? (1)
Chronic kidney disease (CKD).
What is NT-proBNP, and how does it compare to BNP? (2)
NT-proBNP is more sensitive than BNP.
NT-proBNP has greater prognostic value.
Why is troponin a poor marker for reinfarction?
Remains elevated for 3–10 days.
Poor indicator for reinfarction.
What is an “international unit” (IU) in chemical pathology? (2)
A unit to show the concentration of an enzyme (e.g., the upper limit of normal for ALT is 40 IU/liter).
1 international unit is the quantity of enzyme that catalyzes 1 μmol of substrate in a minute (at a given temperature and pH).
