Creatine Kinase In Serum

More Specific Terms

The Kodak Ektachem Clinical Chemistry Slide ( CK), quantitatively measures creatine kinase activity in serum or plasma. CK is a Multiple-Point Rate Test.
The Kodak Ektachem Clinical Chemistry Slide ( CK) is a dry, multilayered, self-contained analytical element coated on a transparent polyester support.
An 11 uL drop of specimen is deposited on the slide & evenly distributed by the spreading layer, this layer also contains N-acetylcysteine ( NAC) to activate CK without pretreating the sample. The reagent layer contains an adenylate kinase inhibitor, diadenosine pentaphosphate, as well as all the components ( enzymes, buffers, dye precursors) necessary for the measurement of CK activity. When the sample is deposited on the slide, creatine kinase catalyzes the conversion of creatine phosphate & ADP to creatine & ATP. In the presence of Glycerol Kinase ( GK), glycerol is phosphorylated to L-a- glycerophosphate by ATP. Oxidation of L-a- glycerophosphate to dihydroxyacetone phosphate and hydrogen peroxide occurs in the presence of L-a- glycerophosphate oxidase (a-GPO). Finally, a leuco dye precursor is oxidized by hydrogen peroxide in the presence of peroxidase (POD) to form a dye. Reflection densities are monitored during incubation. The rate of change in reflection density is then converted to the measurement of enzyme activity. The assay wavelength is 670 nm. The assay time is approximately 5 minutes, and the assay temperature is 37 C.

Creatine Kinase, also referred to as creatine phosphokinase, is a cellular enzyme with a wide tissue distribution. CK is found mainly in skeletal & cardiac muscle. CK's physiological role is associated with ATP generation for contractile or transport systems. Serum CK is almost always increased following acute myocardial infarction and/or skeletal muscle damage. The enzyme is commonly elevated in myocarditis of any cause, cerebrovascular accidents, rhabdomyolysis, polymyositis, & acute physical exertion. CK is also increased in the muscular dystrophies; in Duchenne Muscular Dystrophy. CK elevations of 20-200 times normal are common. Low CK may reflect decreased muscle mass or muscle wasting. Reference values for CK must consider the age, gender, & physical activity of the person. Low serum CK activities are common in the elderly, in the bedridden, & in patients with far-advanced malignancy.

The recommended specimen is 11 uL of serum or plasma. EDTA & sodium fluoride/ potassium oxalate should not be used as anticoagulants. Heparin may be used as an anticoagulant. Collect specimens by standard venipuncture technique. No special preparation is necessary. Special Precautions: CK is unstable in serum. Remove serum promptly from the clot & analyze as soon as possible. Moderate hemolysis does not interfere with the assay, although grossly hemolyzed specimens should not be used. Refrigerate specimens as 2-8 C if analysis is not performed within 4 hours, or freeze specimens at -18 C if analysis is delayed beyond 48 hours.
Minimum sample size is 0.5 milliliter; with an optimum size of 1.0 mL or larger.
Samples that have CK activities that exceed the analyzer's dynamic range should be diluted with an inactivated serum pool, or Kodak Ektachem Solution (7% BSA)/ Bovine Serum Albumin. Multiply results by the dilution factor to obtain the original sample's CK activity. The dynamic range for CK on the Kodak Ektachem 700 is 20 - 1600 U/L.

Kodak Ektachem 700 Analyzer Operator's Manual, Kodak Clinical Products, Rochester, New York.
Kodak Ektachem Slide Package Inserts, Kodak Clinical Products Rochester, New York.
Kodak Ektachem Training Manual, Kodak Clinical Products, Rochester, New York.
Clinical Guide to Laboratory Tests, 3rd edition, NW Teitz (ed), WB Saunders, Philadelphia, 1995.
Clinical Diagnosis & Management by Laboratory Methods, 19th edition, J.B. Henry (ed), W.B. Saunders Co., Philadelphia, PA. 1996, pg 10.

creatine kinase (CK) in serum