CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
In the Lab
FIGURE 12-30 Cystine crystals.
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Learning.
FIGURE 12-31 Leucine crystals.
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FIGURE 12-32 Tyrosine crystals.
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Learning.
FIGURE 12-33 Starch granules.
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FIGURE 12-34 Cotton or other
plant fibers.
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are most amino acids. Leucine crystals are present in some liver conditions, as well as
the amino acid tyrosine. Cholesterol crystals are sometimes seen, while sulfa crystals
are less common due to the newer sulfa drugs in use today.
Artifacts and Other Formed Elements Found in Urine Sediment
A number of microscopically visible elements may be found when examining urine
sediment (Figured 12-33 and 12-34). Most of these are due to diet and/or environment
and are not to be confused with substances that are clinically significant. One thing
that is important for the beginning laboratory student to remember is that the finding
of a single unusual component of the urine is not clinically significant. The clinically
significant elements will be found in considerable numbers in most instances. If a
urine sediment is allowed to dry in the system used for enumerating elements from
the urine, the results can be quite distracting. Artifacts are to be recognized but
are not to be reported. Mucus is not a clinically significant finding, but is reported as
1 through 4+.
Confirmatory Tests for Positive Urinary Chemistry Findings
A multitude of factors may be involved in yielding a positive protein in a urine sample that
is not truly an excretion of protein from the kidneys. Lysed red blood cells, mucus (mucin),
myoglobin, and others will give a false-positive result. It is necessary to follow up on a
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