Partial 2 - Enzymes

Question 1

IU/L

Answer 1

Amount of enzyme necessary to catalyze the conversion of 1μmol of substrate per minute

Question 2

SI unit (mol/sec)

Answer 2

Amount of enzyme that will catalyze the conversion of one nanomole of substrate per second (nanokatal)

Question 3

Enzyme concentration may change if:

Answer 3

• Tissue is undergoing injury
• Tissue is under stress - corrective response
• Tissue is under direct damage: reversible - small molecules; permanent - total leakage
• Tissue Stimulation
• Tissue Proliferation - natural cell turnover

Question 4

How many isoenzymes Lactose dehydrogenase have?

Answer 4

5, LDH1 - LDH5

Question 5

Where in the cell is LDH found and what is the function

Answer 5

Found in cytoplasm of every cell and it catalyze important step glycolysis

Question 6

LDH subunits

Answer 6

H (heart) subunit (gene on chromosome 12)

M (muscle) subunit (gene on chromosome 11)

Question 7

Creatine Kinase (CK) location in cell

Answer 7

Mitochondria

Question 8

CK function

Answer 8

Function in muscle cells to catalyze the transfer of high energy bond from ATP to creatine and irreversible reaction during active muscle contractions

Question 9

CK isoenzymes and their distributions

Answer 9

CK-MM - heart (79%) and muscle (99%)
CK-MB - trace level in muscle (1%) and high level in myocardium (20%)
CK-BB - throughout the brain (97%) and muscles (1% - cardiac muscle)

Question 10

First sign of acute MI biomarkers

Answer 10

First sign is increased myoglobin (small size) and CK-MB isoforms (normal serum trace levels)

Question 11

CK-MB :
Beginning of elevation
Max. peak
Presence

Answer 11

Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: 36-48h

Question 12

Troponins:
Beginning of elevation
Max. peak
Presence

Answer 12

Beginning of elevation: 3-12h
Max. peak: 8-24h
Presence: <10 days

Question 13

Myoglobin:
Beginning of elevation
Max. peak
Presence

Answer 13

Beginning of elevation: 1-4h
Max. peak: 6-7h
Presence: <24h

Question 14

LDH:
Beginning of elevation
Max. peak
Presence

Answer 14

Beginning of elevation: 6-12h
Max. peak: 24-48h
Presence: 6-8 days

Question 15

Skeletal muscle disease useful biomarkes

Answer 15

CK

Question 16

Acute muscle enzyme release causes

Answer 16

Surgery
Trauma
Crush injuries
Excessive muscular contractions
Hyperthermia
Viral myositis
Toxins exposure

Question 17

Muscular dystrophies

Answer 17

Higher portion of CK-MB in muscle than normal (high tissue turnover)

Question 18

Long distance runners

Answer 18

High non-cardiac CK-MB

Question 19

Amylase (Amyl) isoenzymes

Answer 19

Pancreas, salivary gland, testis, ovary

Question 20

Amylase reference range

Answer 20

20-160 U/L

Question 21

Lipase (Lip) reference

Answer 21

<200 U/L

Question 22

Acute pancreatitis diagnosis

Answer 22

• Amylase and lipase level increases after few hours after onset, remain elevated for 36-48h, activity isn’t correlated with severity
• Clinical sensitivity for amylase and lipase - 90% when blood is sampled in the first 36h

Question 23

Pancreatic enzymes in other disorders

Answer 23

Pancreatic trauma
Abdominal surgery
Carcinoma
Diabetes mellitus
Viruses injury
Drugs
Perforated ulcer
Peritonitis
Renal failure (Amylase and trypsin are excreted with urine)

Question 24

Liver Function Tests

Answer 24

• ALT or SGPT
• AST or SGOT
• LDH
• ALP, GGT
• Bilirubin (total and direct)
• Total protein (albumin and globulins)
• Albumin (main protein made by liver)
• PT (pro-thrombin time)

Question 25

Normal ALT and AST levels

Answer 25

10-40 U/l

Question 26

Classic ALT rise

Answer 26

1. Liver injury 2. Muscle myolysis 3. Ischemia 4. Myocardial infarction

Question 27

Classic AST rise

Answer 27

1. 100x toxic liver injury by dead cap 2. 10x prolonged acute liver inflammations, crash injuries, muscular dystrophy, rhabdomyolysis in case of poisoning and drug use (statins) 3. Mononucleosis 4. Hypoxia, heart failure, pancreatitis 5. 2-3x in portal circulation stagnation, cholestasis, acute renal failure

Question 28

De Ritis Ratio AST/ALT

Answer 28

AST/ALT>1

Question 29

Increases in both ALT and AST however with prominent ALT rise informs about?

Answer 29

Slight damage of liver cells

Question 30

Prominent AST rise in de Ritis ratio indicates presence of?

Answer 30

Necrosis areas in liver or muscles eg. 2day after AMI AST/ALT>2

Question 31

De Ritis Ratio in acute disorders (viral, infections)

Answer 31

Higher ALT than AST and de Ritis ratio is <1

Question 32

De Ritis Ratio in chronic disorders (severe cells damage)

Answer 32

de Ritis ratio >1

Question 33

Aloholic liver disease de Ritis ratio

Answer 33

de Ritis ratio >6

Question 34

``` Alkaline Phosphatase (ALP) levels in: Adults, Children and Newborns ```

Answer 34

Adults: 20-70 U/l Children: 20-150 U/l Newborns: 50-165 U/l

Question 35

When and why does ALP rise (Physiologic)

Answer 35

1. Placenta ALP: Pregnant women 2. Bones ALP: Grow-up process 3. Intestine ALP: After the meal in people with O or B blood group, During menstruation, Estrogen use, Fatty meal 4. Bones ALP: Convalescence, bones set up, after surgeries

Question 36

When and why does ALP rise (Pathologic)

Answer 36

1. Fractions of liver isoforms: bile and macromolecular: liver disease 2. Bone ALP: Primary and secondary bone diseases (osteomalacia, osteoporosis) 3. Ectopic isoenzymes: Neoplastic diseases (over expression of genes coding placenta, intestines and germinal cells isoenzymes)

Question 37

If source of increased ALP is unclear, what should you order?

Answer 37

GGT or 5'NT

Question 38

Gamma-glutamylotransferase (GGT) reference for men and women

Answer 38

Men: 18-100 U/l Woman: 10-66 U/l

Question 39

What causes raise in GGT

Answer 39

1. Acute and chronic liver, biliary ducts and pancreas problems especially combined with stasis in ducts flow 2. Slight rise is observed in MI 3. GGT rise is induced in some drugs treatment (barbiturates, fenytoin, estrogens) 4. GGT rises in alcohol use

Question 40

Acute hepatitis major biochemical finding

Answer 40

ALT>AST