Biomarkers Flashcards

1
Q

What is the rate limiting enzyme in haem synthesis?

A

ALA synthase (Aminolevulinic acid synthase)

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2
Q

Which enzyme deficiency causes urate overproduction and what condition is it associated with?

A

HGPRT deficiency

-> Lesh-Nyhan syndrome (self mutiliation, choreiform movements, mental retardation, gout)

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3
Q

Which enzyme marker is raised in Rhabdomyolysis?

A

CK-MM (creatinine kinase muscle type)

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4
Q

What is amyloid AA associated with?

A

Chronic inflammation (e.g., rheumatoid arthritis [RA], inflammatory bowel disease [IBD])

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5
Q

Amyloid AL is linked to which condition?

A

Myeloma amyloidosis

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6
Q

Which enzyme marker is raised in a non-smoker with cirrhosis?

A

Alpha-1 antitrypsin (A1AT) deficiency

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7
Q

Which enzyme marker is raised in someone with mumps?

A

Amylase (associated with parotitis)

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8
Q

Which enzyme marker is used to detect gastrointestinal cancers?

A

Carcinoembryonic antigen (CEA)

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9
Q

What is the order of rise of cardiac markers after a myocardial infarction? (5)

A
  1. Myoglobin
  2. Troponin
  3. Creatine kinase-myocardial 4. band (CKMB)
  4. Aspartate transaminase (AST)
  5. Lactate dehydrogenase (LDH)
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10
Q

What are the characteristics of myoglobin as a cardiac marker?

A

Rises first but is not specific to cardiac muscle

Peaks at 4-6 hours and declines within 24 hours

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11
Q

What are the key features of troponin as a cardiac marker? (3)

A

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

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12
Q

What are the features of creatine kinase-myocardial band (CKMB) as a cardiac marker? (2)

A

Rises after 6 hours of chest pain onset

Peaks at 12-24 hours and declines within 48 hours

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13
Q

Where is alkaline phosphatase produced? (BLIP)

A

Liver, bone, placenta, intestines

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14
Q

What are the causes of raised alkaline phosphatase? (4) (in bone, liver, pregnancy, childhood)

A

Bone: Paget’s disease, osteomalacia, tumors, fractures

Liver: Cholestasis, cirrhosis, infiltrative diseases, hepatitis

Pregnancy (3rd trimester)

Childhood (during growth spurts)

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15
Q

What are the types of creatine kinase and their locations? (3)

A

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)

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16
Q

What are the causes of raised creatine kinase? (5)

A

Muscle damage (e.g., rhabdomyolysis, trauma)

Statin-related myopathy

Duchenne muscular dystrophy (DMD)

Myocardial infarction (MI)
Excessive exercise

17
Q

What is found in very high levels in acute pancreatitis?

A

Amylase (needs to be 3x upper limit to be diagnostic)

Typically will be 10x high(higher than any other cause of high amylase)

18
Q

When is amylase raised? (6)

A

Renal insufficiency
Intestinal infarct/ peritonitis
Cholecystitis
Salpingitis
Ectopic pregnancy
Abdominal cancers

19
Q

What serum enzyme is 3x upper limit and specific to acute pancreatits?

A

Lipase (most specific than amylase)

Tends to be 3x higher, not 10x higher like amylase

20
Q

What is brain natriuretic peptide (BNP)? (3)

A

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.

21
Q

Where is BNP released from?

A

The ventricles of the heart, in response to stretch

22
Q

What to levels of BNP indicate?

A

Low levels <100 : highly specific to EXCLUDE heart failure

High levels >400 : highly sensitive for heart failure

23
Q

What does BNP do systemically?

A

reduces systemic vasoconstriction, sodium retention, and renal sympathetic activity.

24
Q

What is a key confounding factor in the interpretation of BNP? (1)

A

Chronic kidney disease (CKD).

25
Q

What is NT-proBNP, and how does it compare to BNP? (2)

A

NT-proBNP is more sensitive than BNP.
NT-proBNP has greater prognostic value.

26
Q

Why is troponin a poor marker for reinfarction?

A

Remains elevated for 3–10 days.
Poor indicator for reinfarction.

27
Q

What is an “international unit” (IU) in chemical pathology? (2)

A

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).