Lec 3: CK/LD

Question 1

In what Enzyme Classification does CK fall under?

Answer 1

Transferase

Question 2

Other names (2) of Creatine Kinase

Answer 2

• EC 2.7.3.2
• Adenosine triphosphate: creatine N-phosphotransferase

Question 3

[ TRUE or FALSE ]

CK is a dimeric transferase enzyme

Answer 3

TRUE

Question 4

CK Sample Collection

1. Preferred sample
2. Tissue sources

Answer 4

1. • Serum
   • Plasma (lithium heparin)
   • CSF (specialized situations)
2. a. High activity:
   
   • skeletal muscle
   • heart muscle
   • brain tissue
     b. Small quantities
   • bladder, placenta, GIT, pancreas, kidney, spleen, liver
   • Thyroid, lungs
   • uterus, prostate

Question 5

CK levels are sensitive markers for ___. (3)

Answer 5

• AMI
• Rhabdomyolysis
• Muscular Dystrophy (Duchenne’s Muscular Dystrophy)

Question 6

DMD is the most common type of muscular dystrophy affecting ___ males at birth.

Answer 6

5000

Question 7

• characterized by progressive muscle degeneration and weakness
• levels rise 50 to 100 times above the upper limit of normal

Answer 7

Duchenne’s Muscular Dystrophy

Question 8

Conditions that cause elevated CK levels

Answer 8

1. CNS disorders
   
   • damage the blood-brain barrier
2. Hypothyroidism
3. Malignant hyperpyrexia / Malignant Hyperthermia
   
   • reaction to general anesthesia
   • increased body temperature, severe muscle contraction
4. Reye’s syndrome
   
   • causes brain & liver damage
5. Direct muscle trauma

Question 9

Total CK levels have been used as an early diagnosis of ____ infections and ____ pregnancy.

Answer 9

• Vibrio vulnificus
• Ectopic pregnancy

Question 10

CK is a dimer. What are its 2 subunits?

Answer 10

B subunit & M subunit

Question 11

CK ISOENZYME

1. Has the slowest mobility
2. Migrates the fastest to anode
3. major isoenzyme in the sera of healthy people
4. Present in small quantities in the sera of healthy people
5. Most commonly associated with the heart
6. Elevates mostly during injury to cardiac & skeletal muscle
7. Myocardium is the only tissue from which it enters the serum
8. Highest concentrations of CK-BB are found in?
9. Why is CK-BB of brain origin rarely found in serum?

Answer 11

1. CK-MM
2. CK-BB
3. CK-MM
4. CK-BB
5. CK-MB
6. CK-MM
7. CK-MB
8. CNS, GIT, uterus during pregnancy
9. Its molecular weight hinders it from passing the blood-brain barrier

Question 12

CK-MB

• rise:
• peak:
• return to normal:

Answer 12

• rise: 4 to 8 hours
• peak: 12 to 24 hours
• return to normal: 48 to 72 hours

Question 13

The variations in enzyme isoenzyme that deviate from the normal patterns expected in clinical test

Answer 13

Atypical Isoenzyme fraction

Question 14

• migrates to a position between CK-MM and CK-MB
• largely composed of CK-BB complexed with immunoglobulin
• age and sex related

Answer 14

Macro-CK

Question 15

• mitochondrial CK
• migrates to a point cathodal to CK-MM
• typically not present in MI
• not present in normal serum
• indicator of severe illness

Answer 15

CK-Mi

Question 16

methods used in Creatine Kinase measurement

1. It reveals molecules such as Adenylate Kinase that might not be visible with other methods
2. This separates molecules based on their charge
3. Based on #2, what is the resin used?
4. It measures the concentration of enzyme protein
5. It uses antibodies against both M and B subunits to determine CK-MB activity
6. What is the major disadvantage of immunoinhibition?
7. It detects enzymatically inactive CK-MB
8. This involves using portable devices to quickly measure CK levels at the patient spend side or near patient setting

Answer 16

1. Electrophoresis
2. Ion exchange chromatography
3. Ion exchange resin:
   Diethylaminoethyl sephadex A-50 (pH 8)
4. Immunoassay
5. Immunoinhibition
6. Detects CK-BB (false high)
7. Immunoassay
8. Point of care testing

Question 17

This enzyme is released from erythrocytes in hemolyzed samples which potentially leads to falsely elevated CK or CK-MB values

Answer 17

Adenylate kinase

Question 18

The most common interference in CK

Answer 18

Adenylate kinase

Question 19

A band cathodal (migrating slower) to CK-MM

Answer 19

Adenylate kinase

Question 20

Other names (2) of LDH

Answer 20

• EC 1.1.1.27
• L-lactate: NAD + oxidoreductase

Question 21

This enzyme catalyzes the interconversion of lactate and pyruvate using NAD or NADH

Answer 21

LDH

Question 22

The enzyme classification of LDH

Answer 22

Oxidoreductase

Question 23

LDH Sample Collection

1. Preferred sample
2. Other samples used for special testing assays
3. Tissue sources

Answer 23

1. Serum
2. CSF, urine
3. A. High activity
   
   • heart, erythrocytes, kidney, liver, skeletal muscle
     B. Small quantities
   • brain, lungs, smooth muscle

Question 24

LDH

• rise:
• peak:
• remains elevated for:

Answer 24

• rise: 12 to 24 hours
• peak: 48 to 72 hours
• remains elevated for: 10 days

Question 25

The molecular weight of:

1. CK
2. LDH

Answer 25

1. 82,000 Daltons
2. 128,000 Daltons

Question 26

LDH Isoenzymes

1. Elevated most frequently with pulmonary involvement
2. Migrates most quickly toward the anode
3. Has the greatest clinical significance in the detection of hepatic disorders
4. More abundant in the red blood cells
5. Elevated levels will depict muscular dystrophy
6. Major isoenzyme fraction in the sera of healthy individuals
7. More abundant in the heart

Answer 26

1. LD-3
2. LD-1
3. LD-5
4. LD-2
5. LD-5
6. LD-2
7. LD-1

Question 27

It is a rare and atypical isoenzyme of LDH, and not commonly found in healthy individuals

Answer 27

LD-6

Question 28

The 4 methods of measurement of LDH

Answer 28

• Electrophoresis
• column chromatography
• immunoinhibition
• substrate affinity

Question 29

Methods used in LDH measurement

1. Antibody to the M subunit is added where in M subunit will bind to the antibody — rendering the protein inactive
2. Widely used historically and detects fluorimetrically or colorimetrically
3. The measurement of a-hydroxybutyrate dehydrogenase activity
4. This method is used to isolate LD-1 and LD-2 which is important for diagnosing heart attacks
5. In this method, LD-1 should be the only fraction showing enzyme activity
6. This process involves using a technique that combines LD-1 and LD-2 with CK-MB fraction.
7. Why is a-hydroxybutyrate dehydrogenase used to measure the LD-1 fraction?
8. This method is not entirely specific to the LD-1 fraction

Answer 29

1. Immunoinhibition
2. Electrophoresis
3. Substrate affinity
4. Column chromatography
5. Immunoinhibition
6. Column chromatography
7. Because H subunits have a greater affinity than M subunits
8. Substrate affinity