L4-5 - Enzymology

Question 1

What 3 enzymes in the blood can indicate myocardial infarction?

Answer 1

Creatine kinase (CK) 
Lactate dehydrogenase (LD)
Aspartate aminotransferase (AST)

Question 2

What enzyme can be used to diagnose pancreatitis?

Are the levels of this enzyme high or low?

Answer 2

Amylase - high indicates pancreatitis

Question 3

Why is creatine kinase (CK) stored in muscle?

Answer 3

It produces ATP, which muscle need a lot of

Question 4

What demographic typically has a higher creatine kinase level? Why?

Answer 4

Males - usually have increased muscle mass, and CK is stored in muscle

Question 5

How many isoforms does creatine kinase have?

Answer 5

3 found in different muscle types

Question 6

What can lead to creatine kinase being present in the blood?

Answer 6

Leakage from muscle - this can indicate myocardial infarction

Question 7

How many isoforms does lactate dehydrogenase (LD) have?

Answer 7

5

Question 8

What lactate dehydrogenase isoforms are cancer markers? What cancers can they indicate?

Answer 8

LD1 and LD2 - high levels can indicate ovarian or testicular cancer

Question 9

Lactate dehydrogenase isoforms LD1 and LD2 are cancer markers. What else can these isoforms indicate?

Answer 9

Haemolysis of the sample or cardiac damage

Question 10

What conditions can result in increased lactate dehydrogenase?

Answer 10

Tissue damage and some solid tumours

Question 11

Are there any states where an increased alkaline phosphatase (ALP) is healthy?

Answer 11

After eating and during pregnancy

Question 12

What disease states can cause an increase in alkaline phosphatase (ALP)?

Answer 12

Bile duct obstruction, bone/germ cell tumours (depending on isoform)

Question 13

What can cause a decreased gamma-glutamyl transferase (GGT)?

Answer 13

Eating - levels decrease after eating

Question 14

What can cause an increased gamma-glutamyl transferase (GGT)?

Answer 14

Obesity, alcoholic liver disease

Question 15

What are the aminotransferases?

Answer 15

Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)

Question 16

What is aspartate aminotransferase (AST) measurement used for?

Answer 16

Liver function test

Question 17

Give three things a raised aspartate aminotransferase (AST) level can indicate

Answer 17

Acute myocardial infarction, burns/trauma, renal disease, musculoskeletal disease, pancreatitis, haemolytic anaemia

Question 18

What is alanine aminotransferase (ALT) measurement useful for?

Answer 18

Monitoring chronic hepatitis B/C

Question 19

What 3 things can a high AST/ALT ratio indicate?

Answer 19

Skeletal muscle disease, infection (e.g. viral hepatitis), drugs (e.g. alcohol, paracetamol)