Abbott CELL-DYN 3200 System Operator's Manual page 115

Section 3
MCH
MCHC
RDW
RBC Flagging
Platelet Parameters
CELL-DYN ® 3200 System Operator's Manual
9140181H—October 2001
The Mean Corpuscular Hemoglobin is the average amount of hemoglobin
contained in the red blood cell expressed in picograms. The MCH is calculated
from the RBC and the HGB as follows:
MCH = (HGB/RBC) x 10
The Mean Corpuscular Hemoglobin Concentration is the ratio of the weight of
hemoglobin to the volume of the average red blood cell expressed in grams per
deciliter. MCHC is calculated from the HGB and the HCT as follows:
MCHC = (HGB/HCT) x 100
Red Cell Distribution Width is a measure of the heterogeneity of the RBC
population. The CELL-DYN 3200 reports a relative RDW equivalent to a CV in
grams per deciliter. The RDW is derived from the RBC histogram using the 20th
and 80th percentiles.
Refer to the "Operational Messages and Data Flagging" subsection of this section
for RBC Flagging information.
Events counted in the RBC/PLT dilution between floating thresholds are included
in the platelet (PLT) data, which is collected using the 0° and 10° sensors. The
lower threshold floats between 1 and 3 fL and the upper threshold floats between
15 and 35 fL. If there is not enough data to determine the PLT count, the lower and
upper thresholds are set at 2 and 35 fL respectively. Once the thresholds have been
determined, the PLT count is derived from the 10° data.
Data can be displayed in two formats. It can be displayed as a scatterplot (0°/10°)
including the RBCs. Data can also be displayed as one of the following three
histograms:
PLT only using 10° data
PLT and RBC using 0° data
PLT and RBC using 10° data
PLT data are shown as a histogram of the 10° data in the following figure.
Events counted in the region below the lower threshold are usually either optical
noise or small particulate matter. Events counted in the region above the upper
threshold are counted as RBCs. If interference with either threshold region exceeds
a predetermined limit, the PLT parameters are flagged accordingly. The flags are
discussed in the last section of this chapter.
Principles of Operation
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