Lec 3: CK/LD Flashcards
In what Enzyme Classification does CK fall under?
Transferase
Other names (2) of Creatine Kinase
- EC 2.7.3.2
- Adenosine triphosphate: creatine N-phosphotransferase
[ TRUE or FALSE ]
CK is a dimeric transferase enzyme
TRUE
CK Sample Collection
- Preferred sample
- Tissue sources
- Serum
- Plasma (lithium heparin)
- CSF (specialized situations)
-
a. High activity:
- skeletal muscle
- heart muscle
- brain tissue
b. Small quantities - bladder, placenta, GIT, pancreas, kidney, spleen, liver
- Thyroid, lungs
- uterus, prostate
CK levels are sensitive markers for ___. (3)
- AMI
- Rhabdomyolysis
- Muscular Dystrophy (Duchenne’s Muscular Dystrophy)
DMD is the most common type of muscular dystrophy affecting ___ males at birth.
5000
- characterized by progressive muscle degeneration and weakness
- levels rise 50 to 100 times above the upper limit of normal
Duchenne’s Muscular Dystrophy
Conditions that cause elevated CK levels
- CNS disorders
- damage the blood-brain barrier
- Hypothyroidism
- Malignant hyperpyrexia / Malignant Hyperthermia
- reaction to general anesthesia
- increased body temperature, severe muscle contraction
- Reye’s syndrome
- causes brain & liver damage
- Direct muscle trauma
Total CK levels have been used as an early diagnosis of ____ infections and ____ pregnancy.
- Vibrio vulnificus
- Ectopic pregnancy
CK is a dimer. What are its 2 subunits?
B subunit & M subunit
CK ISOENZYME
- Has the slowest mobility
- Migrates the fastest to anode
- major isoenzyme in the sera of healthy people
- Present in small quantities in the sera of healthy people
- Most commonly associated with the heart
- Elevates mostly during injury to cardiac & skeletal muscle
- Myocardium is the only tissue from which it enters the serum
- Highest concentrations of CK-BB are found in?
- Why is CK-BB of brain origin rarely found in serum?
- CK-MM
- CK-BB
- CK-MM
- CK-BB
- CK-MB
- CK-MM
- CK-MB
- CNS, GIT, uterus during pregnancy
- Its molecular weight hinders it from passing the blood-brain barrier
CK-MB
- rise:
- peak:
- return to normal:
- rise: 4 to 8 hours
- peak: 12 to 24 hours
- return to normal: 48 to 72 hours
The variations in enzyme isoenzyme that deviate from the normal patterns expected in clinical test
Atypical Isoenzyme fraction
- migrates to a position between CK-MM and CK-MB
- largely composed of CK-BB complexed with immunoglobulin
- age and sex related
Macro-CK
- mitochondrial CK
- migrates to a point cathodal to CK-MM
- typically not present in MI
- not present in normal serum
- indicator of severe illness
CK-Mi
methods used in Creatine Kinase measurement
- It reveals molecules such as Adenylate Kinase that might not be visible with other methods
- This separates molecules based on their charge
- Based on #2, what is the resin used?
- It measures the concentration of enzyme protein
- It uses antibodies against both M and B subunits to determine CK-MB activity
- What is the major disadvantage of immunoinhibition?
- It detects enzymatically inactive CK-MB
- This involves using portable devices to quickly measure CK levels at the patient spend side or near patient setting
- Electrophoresis
- Ion exchange chromatography
-
Ion exchange resin:
Diethylaminoethyl sephadex A-50 (pH 8) - Immunoassay
- Immunoinhibition
- Detects CK-BB (false high)
- Immunoassay
- Point of care testing
This enzyme is released from erythrocytes in hemolyzed samples which potentially leads to falsely elevated CK or CK-MB values
Adenylate kinase
The most common interference in CK
Adenylate kinase
A band cathodal (migrating slower) to CK-MM
Adenylate kinase
Other names (2) of LDH
- EC 1.1.1.27
- L-lactate: NAD + oxidoreductase
This enzyme catalyzes the interconversion of lactate and pyruvate using NAD or NADH
LDH
The enzyme classification of LDH
Oxidoreductase
LDH Sample Collection
- Preferred sample
- Other samples used for special testing assays
- Tissue sources
- Serum
- CSF, urine
-
A. High activity
- heart, erythrocytes, kidney, liver, skeletal muscle
B. Small quantities - brain, lungs, smooth muscle
- heart, erythrocytes, kidney, liver, skeletal muscle
LDH
- rise:
- peak:
- remains elevated for:
- rise: 12 to 24 hours
- peak: 48 to 72 hours
- remains elevated for: 10 days
The molecular weight of:
- CK
- LDH
- 82,000 Daltons
- 128,000 Daltons
LDH Isoenzymes
- Elevated most frequently with pulmonary involvement
- Migrates most quickly toward the anode
- Has the greatest clinical significance in the detection of hepatic disorders
- More abundant in the red blood cells
- Elevated levels will depict muscular dystrophy
- Major isoenzyme fraction in the sera of healthy individuals
- More abundant in the heart
- LD-3
- LD-1
- LD-5
- LD-2
- LD-5
- LD-2
- LD-1
It is a rare and atypical isoenzyme of LDH, and not commonly found in healthy individuals
LD-6
The 4 methods of measurement of LDH
- Electrophoresis
- column chromatography
- immunoinhibition
- substrate affinity
Methods used in LDH measurement
- Antibody to the M subunit is added where in M subunit will bind to the antibody — rendering the protein inactive
- Widely used historically and detects fluorimetrically or colorimetrically
- The measurement of a-hydroxybutyrate dehydrogenase activity
- This method is used to isolate LD-1 and LD-2 which is important for diagnosing heart attacks
- In this method, LD-1 should be the only fraction showing enzyme activity
- This process involves using a technique that combines LD-1 and LD-2 with CK-MB fraction.
- Why is a-hydroxybutyrate dehydrogenase used to measure the LD-1 fraction?
- This method is not entirely specific to the LD-1 fraction
- Immunoinhibition
- Electrophoresis
- Substrate affinity
- Column chromatography
- Immunoinhibition
- Column chromatography
- Because H subunits have a greater affinity than M subunits
- Substrate affinity
