CLINICAL LAB SCIENEC

4
ESSENTIALS OF CLINICAL LABORATORY SCIENCE
diseases related to clinical signs were also observed and recorded several hundred
years ago. In ancient Egypt, diabetes mellitus was diagnosed by determining
if there was a high level of glucose in the urine of patients; this excreted product
was known to attract ants. It is also probable that some physicians tasted the
urine specimens from their patients, if spoken accounts are to be believed, to
determine if the patient had an abnormal amount of glucose in the urine.
Early in the history of the United States and in other countries, blood-letting
was also an acceptable treatment, as it was believed that “bad blood,” or humors
(liquids of the body), could be removed by bleeding the patient. These crude procedures
were practically the only tests available for the physician for centuries.
Many advances were made, including basic specimen examinations, to improve
the practice of laboratory medicine, particularly during the latter part of the
Middle Ages. As a multiplicity of diagnostic tests became available and more
sophisticated test methods were devised, the physician in all probability found it
effective to pass on his knowledge to assistants and other physicians and to rely
on personnel trained to aid him in his diagnoses by performing the necessary
tests, some of which required an interpretation of results.
Many of these earlier developments and discoveries were eventually incorporated
into routine laboratory procedures. Some of the procedures developed
by physicians were obviously shared with others, but it sometimes was years
after the technology became available before the knowledge was disseminated.
And, as with other types of technology, it often takes many years to develop
and refine some of the equipment used to perform laboratory examinations. But
today’s technological advances have changed the very face of laboratory practice
with regularity, although many of the basic tests from years ago, such as urine
analysis and blood counts, still comprise the bulk of routine testing. In the late
1600s, a significant event occurred that provided a great deal of impetus to the
diagnosis of disease. Anton van Leeuwenhoek (October 24, 1632–August 30,
1723) was credited with the development of the first compound microscope,
although there is some evidence to the contrary, and this instrument was sufficient
to enable one to observe blood cells, protozoa, parasites, ova and parasites,
and some bacteria.
Marcello Malpighi (March 10, 1628–September 30, 1694), who was also
working with clinical specimens in the 1600s, no doubt used Leeuwenhoek’s
microscope or earlier versions to begin some of the first pathological examinations
so common today. During the 1800s, cell theory and bacteriology were
established with the help of the microscope, and it was discovered that bacteria
could cause a whole host of devastating diseases. More rapid technological
advances for laboratory medicine have also become available as a result of
progress in space technology and military and industrial needs, where equipment
used in those areas was adapted to perform medical laboratory procedures. For
example, the development of small, solid state equipment was no doubt spurred
by the need to monitor physiological and anatomic changes in astronauts as
they operated in a foreign environment. An example of an industrial need being
adapted for the medical laboratory is that of particle counters originally used
to measure the purity of industrial compounds. Electronic impedance when a
particle passes through a small aperture in the instrument originally used in
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