Chempath 23: Enzymes And Cardiac Markers

Question 1

Which 2 organs are most commonly associated with ALP rise in case of pathology ?

Answer 1

Liver

Bone

Question 2

When does bone release excess ALP ?

Answer 2

In pathologically high Osteoblast activity

Question 3

How can you differentiate if the pathology is in the liver or Bone when ALP is high?

Answer 3

Measure GGT. If also high it suggests that the liver has the pathology.

Question 4

List 2 physiological causes of high ALP ?

Answer 4

Pregnancy (ALP is released by the placenta)

Growth spurts in children (bone)

Question 5

Which 2 bone diseases produce a high ALP (> 5X upper limit) ?

Answer 5

Osteomalacia

Paget’s disease

Question 6

List 2 pathologies of the liver that cause a high ALP (> 5X upper limit) ?

Answer 6

Cholestasis

Cirrhosis

Question 7

Which of these causes a high ALP but not more than 5X the upper limit ?

A) Bone fracture
B) Osteomyelitis 
C) Hepatitis 
D) Bone tumours
E) Alcoholic Liver Cirrhosis

Answer 7

E) Alcoholic liver cirrhosis

Cirrhosis of the liver causes a high ALP > 5X the upper limit

The rest are all causes of a high ALP but < 5X the upper limit

Question 8

Which test would you do to confirm acute pancreatitis ?

Answer 8

Serum Amylase (10x upper limit)
Pancreatic Lipase

(salivary glands also produce an amylase isoenzyme - can be raised in parotitis)

Question 9

Which disease that is normally vaccinated against can cause a high Amylase?

Answer 9

Mumps

Causes parotid swelling (parotitis) which releases amylase

Question 10

Which form of Creatine kinase is specific for the heart ?

Answer 10

CK-MB

Question 11

Which form of Creatine kinase is specific for skeletal muscle?Which one is specific for the brain ?

Answer 11

CK-MM

CK-BB

Question 12

Which drug used in treatment of cardiovascular disease can causes myalgia or even Rhabdomyelisis and also raised creatine kinase?

Answer 12

Statins

Question 13

How many hours post MI do troponins start to rise?

Answer 13

4-6 hours

They peak at 12-24 hours and remain elevated for 3-10 days

Question 14

Are cardiac markers used to influence decisions about thrombolysis ?

Answer 14

No they are too slow to rise

Question 15

List 2 cardiac markers that are useful in heart failure ?

Answer 15

ANP (from the atria)

BNP (from the ventricles)

Question 16

List 3 enzymes that are biomarkers for MI ?

Answer 16

Myoglobin
Troponin (best markers)
CK-MB

Question 17

Which enzyme cardiac biomarker rises earliest after an MI ?

Answer 17

Myoglobin

But not very specific

Question 18

Which biomarker is most useful to detect re-infarction after a very recent MI.

Answer 18

CKMB

Question 19

Which liver enzyme is raised in an MI ?

Answer 19

AST

Question 20

Where are most enzymes found

Answer 20

Intracellularly

Question 21

In what order are enzymes released

Answer 21

Cytosolic then sub-cellular

Question 22

Where is alkaline phosphatase found in high concentrations

Answer 22

Liver
Bone
Intestines
Placenta

Question 23

What pathologies cause a rise in ALP <5x the upper limit

Answer 23

Bone - tumours, fractures, osteomyelitis

Liver - infiltrative disease, hepatitis

Question 24

RF for statin-related myopathy

Answer 24

polypharmacy (esp fibrates, cyclosporin)
high dose
genetic predisposition
previous hx of myopathy associated with other statins 
vitamin D deficiency

Question 25

What are other causes of raised CK

Answer 25

muscle damage
myopathy (DMD)
MI
severe exercise
physiological (Afro-caribbeans)

Question 26

When would you measure TPMT activity

Answer 26

before starting patients on a thiopurine ( azothioprine, 6-MP)
marker of therapeutic response/drug toxicity

Question 27

Where are different cardiac enzymes found

Answer 27

Myoglobin - cytosolic
CK-MB - mitochondria and nucleus
Troponins - contractile apparatus

Question 28

What is the diagnostic criteria for MI

Answer 28

Either:
- Rise and fall of troponin or more rapid rise and fall of CK-MB and at least one of...
- Ischaemic symptoms
- Pathological Q waves on ECG 
- ECG changes indicative of ischaemia
- Coronary artery intervention 
OR
- Pathological findings of an acute MI

Question 29

Define one international unit (U) of enzyme activity

Answer 29

the quantity of enzyme that catalyses the reaction of 1 micromol of substrate per minute