RADIOMETER ABL90 FLEX User Manual

ABL90 FLEX reference manual 5. Sensors and optical system
5-45
Correcting for interferences
Fetal hemoglobin (HbF) does not have the same spectrum as adult hemoglobin
(HbA) due to a slight variation in molecular structure. The presence of HbF in a
sample will interfere with the result if a correction is not performed.
It is thus important when measuring hemoglobin levels in premature neonates and
neonates aged 0-3 months, as well as adults suffering from e.g. thalassemia, to
take into account this difference [4], and the ABL90 FLEX analyzer automatically
corrects for HbF.
NOTICE: Hb types other than HbA and HbF interfere with hemoglobin
measurements and are not compensated for in the ABL90 FLEX analyzers.
The diagram below shows the transition from fetal hemoglobin to adult
hemoglobin [5].
This graph is only schematic and cannot be used to determine
FHbF.
If the difference between the adult and fetal types of hemoglobin is not taken
into account in measurements on samples containing HbF (e.g. from premature
neonates and neonates aged 0-3 months) then a deviation in the measurement
will arise.
The deviation is most important for measurements of oxygen saturation (
sO
2
and FO
2
Hb) and the fraction of carboxyhemoglobin (FCOHb), since inaccurate
measurements of these parameters can lead to incorrect diagnostic
interpretation of the results, and consequent risk of inappropriate treatment.
The presence of HbF in a sample is detected from the difference spectrum
between fetal and adult oxyhemoglobin. From the size of the difference
spectrum the concentration of fetal oxyhemoglobin,
cO
2
HbF, can be determined.
The amount of cO
2
HbF exceeding a certain level indicates HbF interference. The
analyzer automatically corrects for this interference by subtracting the
difference spectrum of fetal oxyhemoglobin from the measured spectrum.
Repressing the spectra of the likely interfering substances is done in two ways
depending on the substance:
 Either the substance is taken account of in the calculation of the matrix of
constants, K. This applies to Intralipids and Sulfhemoglobin.
 Or the substance is detected, and the measured spectrum is corrected
accordingly. This applies to HbF.
HbF versus
HbA
Deviation of
results
Detecting HbF
Correcting for
HbF
Repressing
spectra

RADIOMETER ABL90 FLEX Specifications

General

Brand	RADIOMETER
Model	ABL90 FLEX
Category	Measuring Instruments
Language	English