CLINICAL LAB SCIENEC

214
ESSENTIALS OF CLINICAL LABORATORY SCIENCE
Common Metric Equivalents
Mass
1 × 10 -3 kg = 1 gram (g) .001 kg
1 × 10 -3 g = 1 milligram (mg) .000001 g
1 × 10 -3 mg = 1 microgram (mcg) .000000001 mg
1 × 10 -3 mcg = 1 nanogram (ng) .000000000001 mcg
Volume
10 3 mL = 1 L
10 3 μL = 1 mL
10 2 mL = 1 dL (10 squared = 100 mL, or 1 dL [deciliter])
Converting Temperature from Degrees Fahrenheit to
Degrees Celsius
Temperature conversions are also required in many chemistry calculations.
Degrees Celsius (ºC) is the standard method of temperature measurement for
scientific operations. Most households in the United States still use the Fahrenheit
(ºF) scale for body temperature measurement, and household appliances most
often use the Fahrenheit scale (Figure 9-3).
Formula for Converting Fahrenheit to Celsius
Values for conversions where C = 32° and F = 56° are as follows:
C = 5/9 (F – 32) Example 5/9 × (56 – 32) = 0.556 × 24 = 13.3°C
F = 9/5 (C) + 32 Example 9/5 × 32 + 32 = 1.8 × 32 + 32 = 89.6°F
94
Fahrenheit
Thermometer
A
Celsius
Thermometer
B
96 98 100 102 104 106 108
98 100
34 35 36 37 38 39 40 41 42 43
36
37 38
A reading of 98.6°F
is the average
“normal” Fahrenheit
body temperature.
A reading of 37°C
is the average
“normal” Celsius
body temperature.
FIGURE 9-3 (A) Fahrenheit and (B) Celsius Thermometers used in
measuring body temperature.
Source: Delmar/Cengage Learning.
A chart is in many cases the most convenient
for conversions from Fahrenheit to Celsius and
vice versa. Some common numbers that may be
converted are shown in Table 9-5.
International System of
Units (SI)
Although an attempt to standardize the reporting
of laboratory results by using SI units has been
underway for at least 40 years in this country,
a great deal of resistance has been encountered.
Tests were performed and reported as milligrams
or grams per deciliter before the SI system
came to the forefront in many countries. The
SI system uses actual cell counts and millimoles
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