Chempath - enzymes and cardiac markers

Question 1

In cell necrosis, which enzymes are released first - cytosolic or sub cellular?

Answer 1

Cytosolic first, then subcellular

Question 2

If an enzyme is released by many different tissues, how can you identify which tissue it is released by?

Answer 2

Enzyme isoforms - these can be specific to a tissue

Question 3

name 4 tissues which release ALP at high concentrations

Answer 3

Liver
Bone
Intestine
Placenta

Question 4

3 ways liver and bone ALP can be differentiated

Answer 4

GGT measurement
Electrophoresis
Bone specific ALP immunoassay

Question 5

2 physiological causes of raised ALP

Answer 5

Pregnancy in the 3rd trimester

Growth spurt in childhood

Question 6

> 5x the upper limit of normal ALP - give 4 pathological causes

Answer 6

Bone - PAGETS, OSTEOMALACIA

Liver - Cholestasis, cirrhosis

Question 7

<5x the upper limit of normal ALP - give 5 causes

Answer 7

Bone - Tumours, fractures, osteomyelitis

Liver - infiltrative disease, hepatitis

Question 8

When is ALP raised in osteoporosis

Answer 8

When it’s complicated by fractures

Question 9

Amylase is raised in acute pancreatitis. Which test is more specific?

Answer 9

Lipase

Question 10

3 forms of creatine kinase - which muscles release them?

Answer 10

MM = skeletal
MB = cardiac muscles
BB = brain (activity is minimal)

Question 11

Risk factors for statin related myopathy

Answer 11

High statin dose
Prev Hx of statin related myopathy
Polypharmacy w other drugs also metabolised by CYP3A4

Question 12

5 causes of a raised CK

Answer 12

Myopathy
MI
statin 
severe exercise
Physiological - esp afrocaribbeans

Question 13

An 82 year old women presented with bone pain, history of fractures and bowing of her tibia. Which enzyme measurement might be helpful with the diagnosis?

Answer 13

ALP

Question 14

A 64 year old man who smokes and has a family history of cardiovascular disease has recently been started on atorvastatin. Three weeks after commencing the tablet, he complains of generalised muscle pain. What is the working clinical diagnosis?

Answer 14

Statin related myopathy

Question 15

What measurement is taken in patients being considered for azathioprine/6-mercaptopurine?

Answer 15

TPMT

Question 16

Current marker of choice for Myocardial injury? When does it start to rise? When does it peak?

Answer 16

Troponin

Rise at 4-6 hours
Peak at 12-24 hours

Question 17

When is troponin level measured in chest pain?

Answer 17

6 and 12 hours post onset of chest pain

Question 18

How can cardiac biomarker levels help with deciding if MI requires thrombolysis?

Answer 18

They don’t rise quickly enough so they can’t. Decision is clinical

Question 19

2 biomarkers in heart failure?

Answer 19

ANP

BNP

Question 20

If someone gives a history of an MI from 1 week ago, which biomarker measurement will be most useful?

Answer 20

Troponin - remains raised for 3-10 days

Question 21

How do we measure enzyme activity?

Answer 21

IU = international unit

Amount of enzyme needed to catalyse a reaction so that 1micromol of substrate is made