48
| 3 | 2011
Klinisk Biokemi i Norden
SKUP evaluation:
HemoCue® WBC for B–Leukocytes
Arne Mårtensson
EQUALIS AB, Uppsala
The HemoCue® WBC system (HemoCue WBC)
measures the “number concentration” of leukocytes
in blood (B–Leukocytes) and is intended for use in
primary health care. HemoCue WBC is manufactu-
red by HemoCue AB, Sweden, and supplied in the
Scandinavian countries by the HemoCue subsidiary
companies. The HemoCue WBC system consists of
the HemoCue WBC Analyzer and the HemoCue WBC
Microcuvettes. The measurements can be done on
whole blood from a capillary finger prick or a venous
sample. The sample volume, about 10 µL, is achieved
by filling the microcuvette. After the placement of the
filled microcuvette in the instrument, the procedure
is automatic. HemoCue WBC counts the number of
stained leukocytes in the microcuvette by image ana-
lysis. The result is displayed on the screen at the end
of the test. The measuring range is 0,3 to 30,0 x 10
9
/
L.
Measurement duration is 3 minutes.
This evaluation was carried out in a hospital
laboratory with venous samples, and at two primary
care centres with venous and capillary samples. The
comparison method was the measurement of venous
samples with an Advia 2120 cell counter at the Depart-
ment of Clinical Chemistry, Södra Älvsborgs Sjukhus
(
SÄS), Borås, Sweden. The method is accredited by
Swedac.
Quality goals
The quality goal for imprecision was ≤5.5%, and the
bias should not exceed ±6.0%. The quality goal for
total error was that 95% of the HemoCue WBC results
should not deviate more than ±18% from the compa-
rison method results. The theoretical limits of ±15%
had then been widened with ±3% considering the
analytical quality of the comparison method. Fraction
of technical errors should be <2%.
Results
Venous samples in the hospital laboratory The estima-
ted CV obtained with all venous samples was 3.1%. The
between-days imprecision for patient sample results
and for control blood results was 4.4%. The HemoCue
WBC results with venous samples fulfilled the quality
goal for precision.
HemoCue WBC showed different bias depending
on the level of B–Leukocytes. The results were divided
into three concentration level groups. The results in
the low and high level groups showed almost no bias.
The results in the medium level group (3.8 to 7.7 x
10
9
/
L) showed a negative bias of −6.6%. The HemoCue
Figure 1. Picture of HemoCue WBC Analyzer
