Klinisk Biokemi i Norden Nr 1, vol. 20, 2008 - page 48

48
| 1 | 2008
Klinisk Biokemi i Norden
Discussion
According to our results, the Konelab™ method shows
good linearity within the measuring range, which
was stated by serially diluting a plasma sample with a
myoglobin concentration of 482 µg/l. The instrument
was capable of automatic dilution of samples with
myoglobin concentration up to 2.600 µg/l and also
no hook effect was found with a sample concentra-
tion of 10,718 µg/l. Parallel measurements using 108
plasma samples showed very small variation between
samples (mean difference 0.03 µg/l). Values using
0.9% NaCl slightly deviated from the zero-point with
6.4 µg/l and the lowest measurement concentration of
the method was calculated to be 12.8 µg/l.
The within and between runs of variation were
acceptably low (Table I) using 24 and 11 replicate
measurement analyses and runs, respectively. Also
the results with control samples at normal and elevat-
ed concentrations showed excellent agreement with
the expected mean values.
The comparison of the results of Konelab™ 20 XTi
with the electrochemiluminescence method on a
Roche Elecsys® 2010 analyzer showed good agree-
Figure 1
.�
y = 1.1795x - 1.1277
0
50
100
150
200
0
50
100
150
200
Konelab myoglobin g/l
Elecsys myoglobin g/l
r=0.947
ment (Figure 1, r = 0.947), although there was a small
difference between the methods, probably caused by
different calibration materials and standardization.
Thus, for more uniform results, a common control
preparation should be available and used by different
manufacturers [4].
Our experiences with the new particle-enhanced
immunoturbidimetric method for myoglobin seems
to be well suited to daily clinical use with the
Konelab™ 20XTi automated chemistry analyzer, or
with other analyzers allowing the use of user-defined
applications and non-system reagents. However,
common international reference material(s) [4] are
sorely needed, as shown by many national [5] and
international external quality control surveys, to
produce more uniform results and to decrease inter-
laboratory variation.
References
[1] Schultz A, Larsen CE, Kristensen SD, Schmidt
EB, Astrup G. Serum myoglobin measured
by latex agglutination: rapid test for exclusion
of acute myocardial infarction. Am Heart J
1986;112:609-10.
[2] Konelab™ Myoglobin, ref. 981847, Thermo
Fisher Scientific Corporation, Vantaa,
Finland.
[3] Penttilä K, Koukkunen H, Halinen M,
Punnonen K, Pyörälä K, Rantanen T, et al.
Serum and plasma samples for selection of
cardiac markers in diagnostics of patients
with acute chest pain. Scand J Clin Lab Invest
2002;62:1-9.
[4] Panteghini M, Linsinger T, Wu AH,
Dati F, Apple FS, Christenson RH, et al.
Standardization of immunoassays for meas-
urement of myoglobin in serum. Phase I:
evaluation of candidate secondary reference
materials. Clin Chim Acta 2004;341:65-72.
[5] ZaninottoM, SciacovelliL,PaganiF,Panteghini
M, Plebani M. External quality assessment for
biological markers of myocardial damage:
an Italian experience. Clin Chem Lab Med
2004;42:1434-41.
Figure 1
Comparison of the Konelab™ myoglobin method to that of
Roche Elecsys® with 77 EDTA-plasma samples from 25 to 154
μg/l.
(Fortsat fra side 47)
1...,38,39,40,41,42,43,44,45,46,47 49,50,51,52,53,54,55,56
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