Theoretical Principles
User Manual Hemo Control
11.3 Calibration
The Hemo Control photometer is calibrated against the reference
cyanmethemoglobin method to determine the proportionality factor K.
This factor is fixed in the device as an individual parameter.
Calibration is performed by the manufacturer against the NCCLS
reference method
and yields results comparable with ICSH (1995)
. A
maximum tolerance of 0.3 g/dL (0.2 mmol/L) at 15.0 g/dL (9.3 mmol/L)
is accepted.
11.4 Calculation of hematocrit value
Hematocrit (Hct) is synonym to PCV (Packed Cell Volume) and means
cell volume of red blood corpuscle (erythrocrit).
If the hemoglobin is inside the normal range, an estimation of the
hematocrit is obtained by multiplying the measured hemoglobin
concentration (expressed in g/dL) by factor 2.94
.
This calculation should not be used outside the normal range of
hemoglobin in humans, e.g. under 120 g/L (7.44 mmol/L) and above 180
g/L (11.16 mmol/L). It should also not be used in anemic conditions
(genetic or caused on serious diseases).
NCCLS, Reference and selected procedures for the quantitative determination of
hemoglobin in blood; approved standard – third edition, NCCLS Document H15-A3, 2000
Recommendations for reference method for haemoglobinometry in human blood (ICSH
standard 1995) and specifications for international haemiglobincyanide standard (4
th
edition)
J.D Bauer, P.G Ackermann, G. Toro, Clinical laboratory methods. The C. V. Mosby
Company, Saint Luis 1974, S. 156
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