Is determination of creatine kinase-2 after electrophoretic separation accurate?
Since 1991, the Ontario Laboratory Proficiency Testing Program has assessed the analytical performance of creatine kinase (CK; EC 2.7.3.2) isoenzyme-2, using fresh human serum supplemented with purified human CK isoenzymes. In Ontario, the 142 laboratories licensed to analyze CK-2 use a variety of methods: electrophoresis-based, immunoinhibition, and mass assays. During a 1992 survey, duplicate CK-2 samples with different total CK activities showed poorer precision when analyzed after electrophoretic separation than by any other method. A 1993 survey designed to validate these observations conclusively showed that electrophoresis-based assays are subject to a bias proportional to the total CK activity. These survey results were confirmed by studies with selected patients' specimens. We therefore conclude that electrophoresis-based assays may not warrant their reputation as the gold standard for CK isoenzyme measurement.
Henderson
A R
AR
Laboratory Proficiency Testing Program, Toronto, Ontario, Canada.
Stark
J A
JA
McQueen
M J
MJ
Patten
R L
RL
Krishnan
S
S
Wood
D E
DE
Webb
S
S
D003402:Creatine Kinase / Q000097:blood*; D004586:Electrophoresis; D006801:Humans; D007118:Immunoassay / Q000706:statistics & numerical data; D007124:Immunoenzyme Techniques / Q000706:statistics & numerical data; D007527:Isoenzymes; D011786:Quality Control; D012680:Sensitivity and Specificity
D007527:Isoenzymes; D003402:Creatine Kinase