CLINICAL LAB SCIENEC

346
ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
with the spectrophotometer in the cell counter.
If it is necessary in a manual procedure to
perform the test on a diluted sample, the result
should be multiplied by the factor of the dilution
(e.g. a 1:2 dilution would require that the
result be multiplied by a factor of 2).
In physician office laboratories and for
point-of-care testing, the use of a direct readout
device called a hemoglobinometer may
be required. A variety of these instruments
designed for point-of-care testing are available
and may be used in place of the manual
procedure outlined below; Hgb determinations
can also be made by the automated systems
in use in large laboratories. The Hgb Pro
FIGURE 13-11 Hgb Pro instrument.
(Figure 13-11) provides a quick and accurate
Source: Delmar/Cengage Learning.
Hgb estimate and requires a very small blood
sample, such as that available by capillary
puncture. For a direct read-out instrument, set the read-out concentration value of
the Standard and read the Unknown concentrations directly.
Although the final reaction for hemoglobin values using methods where cyanmethemoglobin
is formed appears quite stable, the test samples should be read
within 1 hour before evaporation of the reaction solutions becomes significant.
Results should be reported as grams per deciliter (g/dL) or in SI units.
Equipment and Supplies
1. Gloves, disposable paper towels, and disinfectant or other cleaning solution
2. Report form for Procedure #4
3. Cyanmethemoglobin reagent
4. Hgb standard
5. Micropipetter capable of measuring small volumes
6. Pipettes or pipetter for measuring reagent
7. Spectrophotometer or colorimeter calibrated at 540 nm
8. Properly drawn blood sample in an anticoagulated tube or microhematocrit tube
(clots will cause errors in the determination)
9. 13 100 mm test tubes and test tube rack
10. Waterproof sharp marker
11. Electronic timing device or clock/watch with second hand
Procedure
1. Wash hands and don gloves.
2. Assemble necessary equipment and supplies.
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