NCCLS Guidelines on Method Comparison (23), the French Proto–
col for Validatian of Methods (24)-or the procedures accor–
ding to Passing and Bablok (24 a) should be followed.
o
o
2.2 Measurement at 37 C and 30 C
The ECCLS standard Method performs equally well at either re–
action temperature. In routine use and quality assessment re–
sults should
be
reported at the temperature at which the mea–
surements were made.
2.3 Temperature Conversion Factors
However, as discussed in the Introduction, conversion factors
rnay be of use for cornparison of literature data. In evalua–
ting such data the choice of the calibration material and
isoenzyrne cornpositions must be considered. The different CK
isoenzyrnes and MM variants all have different conversion fac-
o
o
tors 37 C/30 C (25-27):
CK MMl
MM2
MM3
MB
BB
ma
c
ro
ma
c
ro
type
I
type
II
2.78
The prevalence of macro CK type
II
is about 3% of all hospi–
talized patients. Clinically, however, it is only 0.5% in
sera with increased total CK catalytic activity concentration
from patients suspected of an acute myocardial infarction
( 24) .
As an example, the average conversion factors recornrnended in
Switzerland and in The Netherlands are 1.60 and 1 ,59 respec–
tively (8).
22
Klinisk kemi i Norden 2: suppl, 1990
