Muscle Enzymes: CK, LD, and Aldolase

Muscle Enzymes

• Creatinine Kinase (CK), also known as Creatinine Phosphokinase (CPK), is classified as E.C. 2.7.3.2 and is an ATP:Creatinine-N-phosphotransferase
• CK reference values vary: Male: 46-300 U/L and Female: 34-180 U/L
• CK can be measured using the Oliver or Rosalki Method: The Flourometric method (Sax & Moore) and Hughes method can also be used
• Lactate Dehydrogenase (LD) is classified as E.C. 1.1.1.27 and is an L-lactate: NAD+ oxidoreductase
• LD forward reaction normal values measure between 125-220 U/L and reverse reaction measures between 297-537 U/L
• LD can be measured using: Wrobleuski-Cabaud, Wrobleuski and La Due, or Wacker et al methods
• Aldolase is classified as E.C. 4.1.2.13 and is a D-fructose-1,6-bisphosphate D-glyceraldehyde-3-phosphate-lyase
• Aldolase normal values fall between 2.5-10 U/L
• Aldolase normal values are 4x higher in neonates, and 2x higher children
• Aldolase can be measured by Pinto, Kaplan and Van Dreal, or Sibley and Lehninger methods
• Glycogen Phosphorylase is classified as E.C. 2.4.1.1 and is a 1,4-alpha-D-glucan:orthosphate and can be measured using Electrophoresis or Coupled assay system
• Troponin can be measured using an Immunoassay
• Cardiac Troponin T (cTnT 1) normal value has a reference measure of <0.40ng/mL

Liver Enzymes

• Aspartate Aminotransferase (AST), also known as Serum Glutamate Oxaloacetate (SGOT), is classified as E.C. 2.6.1.1 and is an L-aspartate-2-oxoglutarate aminotransferase
• AST involves the transfer of an amino group between Aspartate and keto acids for amino acid degradation
• Created ketoacids are oxidized by the tricarboxylic acid cycle
• Pyridoxal-5-phosphate is a key coenzyme
• AST can be measured using the Continuous monitoring method (Karmen et.al)

Cardiac Profile

• Cardiac profiles are requested to establish baseline values
• Blood is drawn every 3 hours for analysis during the first 12 hours of period when testing
• Cardiac profiles used include labs for:
• Cardiac troponin T or I
• CK-MB
• Myoglobin

Markers of Myocardial Infarction

Test | Onset | Peak | Duration

• -- | --- | --- | --- Creatinine Kinase | 3-12 hours | 18-24 hours | 36-48 hours Troponin | 3-12 hours | 18-24 hours | Up to 10 days Lactate Dehydrogenase | 6-12 hours | 24-48 hours | 6-8 days Myoglobin | 1-4 hours | 6-7 hours | 24 hours Aspartate Aminotransferase | 6-8 hours | 24-36 hours | 4-5 days

Levels of LD Isoenzymes in Certain Conditions

Condition | Findings

• -- | --- Normal serum | LD2 > LD1 > LD3 > LD4 > LD5 Acute MI, Acute renal infarction, Hemolysis | LD1 > LD2 (called "flipped") Normal CSCF |LD1 > LD2 > LD3 > LD4 > LD5 Hydrocephalus and seizures |LD2 > LD1 Bacterial meningitis | LD5 > LD4 > LD3 > LD2 > LD1

Electrophoresis: LDH 1 → 2 → 3 → 4 → 5 Concentration: LDH 2 → 3 → 1 → 4 → 5

• LDH-1 was thought to be another enzyme(Alpha HBD)

Aldolase

• Aldolase (ALD) is an D-Fructose-1,6-bisdiphosphate D-glyceraldehyde-3-phosphate-lyase classified as E.C. 4.1.2.13
• Aldolase splits D-fructose diphosphate to D-glyceraldehyde phosphate and dihydroxy acetone phosphate
• This aids in the glycolyou breakdown of glucose to lactate.
• Aldolase’s optimum pH is between 6.8–7.2 Historical methods for testing include: Pinto, Kaplan and Van Dreal, Sibley and Lehninger.
• Considerations intesting include:
• Enzyme activity is stable at ambient temperature for up to 48 hours and at 4C for several days.
• Hemolysis should be avoided, since the red cells contain 10 times as much ALD as Serum.
• Reference value: 2.5-10 U/L
• Normal values are 4x higher in neonate and 2x higher in children
• Increased presence indicates:
• Muscle degeneration indicates Severe elevation
• Gangrene, Megaloblastic anemia, Metastatic liver CA,Viral hepatitis and Granulocytic leukemia, Psychosis, Trichinosis: Moderate elevation

Aldolase Isoenzymes include:

• ALDOLASE A which is found predominantly in skeletal muscles
• ALDOLASE B which is Found in the liver, kidney and WBC
• ALDOLASE Cwhich is Found in the brain tissues
• Amylase is classified as E.C. 3.2.1.1 , is an Alpha-1-glucan-4-glucano-hydrolase, and can be measured using a coupled kinetic method
• Normal amylase values are 31-107 U/L
• Lipase is classified as E.C. 3.1.1.3, is a Triacyl Glycerol Acylhydrolase, and can be mesured using titration methods
• Normal lipase values measure up to 38 U/L
• Glycogen Phosphorylase can be tested for using Electrophoresis and Coupling assay system -Normal values measure up to 7 U/dL
• Acidh Phosphatase can be measured using the Bodansky or Gutman & King-Armstrong tests
• NormalM: 2.5-11.7 U/L and F: 0.3-9.2 U/L
• Prostatic Acid Phosphatase has references of: M: 0.2-5.0 U/L and F: 0.0-0.8 U/L

Lactate dehydrogenase levels

• Test results affected by acute events
• Normal serum gives results of: LD2 > LD1 > LD3 > LD4 > LD5
• Acute MI, Acute renal infarction, Hemolysis measure LD1 > LD2
• Normal CSF measures: LD1 > LD2 > LD3 > LD4 > LD5
• Hydrocephalus and seizures : LD2 > LD1
• Bacterial meningitis: LD5 > LD4 > LD3 > LD2 > LD
• Tests on Lactate Dehydrogenase can be conducted through Electrophoresis: LDH 1 → 2 → 3 → 4 → 5 and by concentration: LDH 2 → 3 → 1 → 4 → 5