CLINICAL LAB SCIENEC

CHAPTER 12: PROCEDURES FOR URINALYSIS AND BODY FLUIDS 293
Performing the Urinalysis
Urine samples will be tested for chemical and microscopic
components in a complete urine analysis.
Only in cases where it is indicated will a urinalysis
be carried further than the basic components listed.
Macroscopic or Physical Exam
The initial examination for the physical properties
of a urine sample (color, volume, and clarity) has
been greatly facilitated by the use of standard collection
procedures.
Chemical Urinalysis
The chemical components are chiefly tested by a
chemical-coated dipstick (also called a reagent
strip) that contains pads that will change colors in
the presence of certain materials in the urine (Figures
12-6 and 12-7). Confirmatory tests may necessary
when the protein or bilirubin is positive with
the dipstick method.
Chemical results from urine samples may be
read by an instrument (Figure 12-8) that scans the
FIGURE 12-5 Scales for determining specific gravity from the
refractometer. Note the section for total protein in plasma
or serum.
Source: Delmar/Cengage Learning.
dipstick. The chemicals are designed to react in the presence of specific analytes
to calculate the semiquantitative value for a number of components. Strips are
available that read as few as 2 results and up to 12 different chemistry determinations.
These strips are used for screening urine samples. If certain tests are positive,
confirmatory testing may be necessary to rule out false positive results and
to quantitate some positive findings, such as those of protein and bilirubin. These
tests are discussed later in this chapter. There are also specialized strips for diabetics,
in which the microalbumin and the creatinine are compared to determine if
early renal disease has occurred.
For manual reading of the reagent strips, care must be taken to dip an uncontaminated
and fresh strip into the urine, and one edge of the strip should be blotted
against a piece of gauze or a paper towel. Using a stopwatch, the times for reaction
FIGURE 12-6 Urine reagent strips for chemistry determination.
Source: Delmar/Cengage Learning.
FIGURE 12-7 Color graph for Bayer Multistix 10 SG.
Source: Delmar/Cengage Learning.
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