CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
Introduction
Several different types of fluids are described as body fluids. Blood is actually a
body fluid but is treated separately from urine and other miscellaneous fluids.
All of the body fluids, which include CSF, urine, synovial (joint) fluids, exudates
and transudates, and tissue fluids, are ultrafiltrates from blood plasma. The levels
of certain constituents in the blood are different from those found in other
body fluids, and these levels are important in providing nurture and protection
to the body. For instance, protein and glucose in the CSF are important in
providing the protection and energy needed by the central nervous system. The
same is true for synovial fluids, which cushion and nourish cartilage found in
the joints of the body.
Changes in urine and body fluids can signal malfunctions in the body ranging
from minor to extremely serious conditions. This chapter is not intended
to be a definitive “how-to” set of materials to teach procedures in urine and
body fluids analyses, but rather is designed to orient the student to the basics
of this important segment of laboratory medicine. It is not intended to teach
anatomy and physiology, although a diagram of the functional unit of the kidney
is presented. Students enrolled in a clinical laboratory program would most likely
have already completed or will be concurrently enrolled in courses in chemistry,
anatomy, and physiology. Separate courses for teaching each major component of
the clinical laboratory program (e.g., urinalysis and body fluids, clinical chemistry,
hematology and coagulation, microbiology, and blood banking) should logically
follow the information in this book.
The material presented in this chapter includes the basics of laboratory medicine,
safety, and pathological conditions for the testing of urine samples and
other body fluids. Some of the figures show equipment the student will be using
in this chapter’s procedures.
Rationale for a Complete Urinalysis
The kidneys perform many vital roles in the metabolism of the human body.
That of maintaining the pH (alkalinity or acidity) of the body within a narrow
range is of utmost importance. Kidney failure where this is not achieved may
lead to an almost immediate death.
The kidneys rid the body of waste products and excess water. If certain
products of metabolism are unable to be cleared from the body due to various
disease processes, their levels may rise until the patient’s life is threatened. If the
nephrons (the functioning units of the kidneys) are damaged or malfunctioning,
they may be unable to do their job. In extreme cases, the patient may require
dialysis with a machine designed to rid the blood of wastes on a regular basis,
sometimes until a kidney is available for transplant. Kidney damage may result
from bacterial infection or trauma where an injury may have cut off the blood
supply to the kidneys and the tissue became necrotic (dead).
Basic laboratory examinations are performed on almost all patients who
have a medical appointment or an emergency visit for treatment, regardless
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