Enzymology

Question 1

Do enzymes have function in the blood

Answer 1

No, function in cells or secretion

Question 2

What is measured in assays

Answer 2

Activity not the mass/concentration

Question 3

When does serum enzyme activity increase

Answer 3

-Increased release
-Increased production
-Decreased removal

Question 4

Increased release “leakage’ Enzymes

Answer 4

Enzymes in cells and are released in blood when cell is damaged. Increases serum activity quickly and the damage can be mild (reversible or irreversible) or cause cell death. Magnitiude of increase depends on number of cells injured, severity, and half life of enzyme

Question 5

Magnitude of increased release or leakage enzymes

Answer 5

Does not tell us if it is reversible or irreversible or focal or diffuse.
Not related to severity of disease

Question 6

How are sub lethal cells able to have a higher magnitude of enzyme leakage

Answer 6

Continued synthesis of the enzymes and there is still leakage

Question 7

Leakage enzymes example

Answer 7

-ALT
-AMS
-AST
-CK

Question 8

Increased production of enzymes

Answer 8

Typically attached to cell membrane and increased mass of enzyme producing cells (hyperplasia or neoplasia) slow process because synthesis needs to be induced

Question 9

What are inducible enzymes not indicators of

Answer 9

Cell damage

Question 10

Decreased removal/inactivation of enzyme

Answer 10

Some enzymes cleared renally and decreased renal function. This is not known for every enzyme

Question 11

Enzymes that increase from decreased removal

Answer 11

AMS and LPS

Question 12

Long half lives and increased activity

Answer 12

The pathologic process may have occurred several days ago
THe enzyme activity will decrease relatively slowly after damage has stopped

Question 13

Short half life and increased activity

Answer 13

The process occurred recently or is ongoing
The enzyme activity will decrease relatively quickly after damage has stopped

Question 14

Sample quality

Answer 14

-Hemolysis (enzymes added)
-Icterus )spectral interference)
-Lipemia (spectral interference) prefer fasted sample

Question 15

Interpretation of increased serum activity

Answer 15

-Variation in enzyme activity by different assays, use appropriate ref interval (compare the magnitude of change between different assays)
-Magnitude of change (may not be accurate, so baseline values are useful)
-Consider half life

Question 16

Significance of increased enzyme activity

Answer 16

Markers of pathologic processes not a specific disease. Always integrate conclusions with patient information