CELL-DYN 3000 System Operator’s Manual 7-19
9140240E — May 1995
Chapter 7 Quality Control
Target Value
The target value for X-B is similar to the assay value for a commercial
control. It is derived from the patient population analyzed on the
instrument.
Action Limit
The action limit is the acceptable limit of variation around the target
value.
Establishing the Target Value
A recent study
6
by Dr. Bull collected data from 1767 hospitals and
yielded the following mean values:
MCV 89.9 fL
MCH 30.5 pg
MCHC 33.9 g/dL
This recent study confirmed values that Bull published in an earlier
study
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. Consequently, the values shown above can be used as the target
values to initiate the X-B analysis program.
Laboratories seeing specialized patient populations, e.g., pediatric
hospitals or tumor centers, may need to verify these values due to
“abnormal” patient populations. Target values may be verified by
evaluating approximately 500 samples and comparing the X-B means for
those samples to the entered target values.
The CV on 500 samples for each index should be
≤ 1.5%. (Dr. Bull’s
study {mentioned in the previous paragraph} found CVs from 0.5% to
1.2%. The 1.5% is one-half the allowable ± 3% action limit, which is
acceptable for this confirmatory step.) If the CVs are >1.5%, an
additional 500 samples should be evaluated.
Interpreting X-B Results
A suggested protocol and guidelines for interpreting X-B data can be
found in Chapter 1 of Laboratory Hematology, An Account of
Laboratory Techniques, edited by I. Chanarin.
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CELL-DYN Controls
Tri-Level, 1 box, 2.5-mL vials x 12, list number 93111-01
Tri-Level, 1 box, 3.0-mL tubes x 12, list number 99129-01
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