CLINICAL LAB SCIENEC

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ESSENTIALS OF CLINICAL LABORATORY SCIENCE
identifying bacterial organisms, which would be performed in the microbiology
department where organisms are also grown and biochemically tested for identification
of some strains of organisms.
Virology and parasitology are usually incorporated into the microbiology
department unless the hospital is extremely large and provides a full range of all
services. Routine urinalysis tests are often performed in other departments rather
than having a single department to perform only urine analyses. For example,
biochemical tests on urine samples may be performed in the clinical chemistry
department. Urinalysis is often performed in hematology unless a large number
of specialized urine analyses are performed, in which case there would probably
be a separate urinalysis department. If the facility is large enough, there might be
a special chemistry department that would perform all biochemical tests except
the basic chemistry procedures from blood samples. Most often, a laboratory is
divided into several major departments, some of which may be combined.
Hematology
Descriptively, hematology means “study of blood.” The Greek word root haema
literally means “blood,” and the suffix –ology means “study” or “science” of a
particular clinical site or body part. An adult human has 5 to 6 liters of blood
in the body. Human blood and the blood of other vertebrates is composed of
a liquid portion called plasma and a solid component composed of formed elements
such as red blood cells (erythrocytes), white blood cells (leukocytes), and
platelets (thrombocytes).
Most laboratory examinations are performed on blood samples and may
include the liquid or the solid portion. Blood carries nutrients for the cells and
oxygen for delivering needed materials to the cells; blood also removes toxic waste
products and carbon dioxide from the body. Specialized proteins derived from the
immune system are also found in the plasma. The function of white cells is chiefly
as a defense against bacteria, viruses, fungi, and protozoa that invade the body.
The basic test performed in the hematology laboratory is the complete
blood count (CBC). The CBC procedure is used to analyze a sample for the number,
size, and shape or type of both white and red blood cells. It is useful in determining
various types of anemia, infection, and abnormalities of the bone marrow
where the cells originate. There are a number of methods for determining and
calculating values for a CBC, ranging from totally automated systems to manual
counts. Other tests commonly completed in the hematology department would
include cell counts from cerebrospinal (CSF) fluid, pleural fluid from around the
cavity containing the lungs and heart, parietal fluid from the abdominal (peritoneal)
cavity, dialysate fluid (from dialysis), and synovial fluid from the joints.
Many major diseases may be determined from the CBC. In some cases, cancer
may be discovered or overwhelming infections of either viral or bacterial
infections are found. Dietary and genetic types of anemias may be diagnosed
from red blood cells, and cancer of the bone marrow (leukemias) of many types
may be found here. Also, deficiencies and abnormalities of the platelets (thrombocytes)
that aid in clotting may be evaluated. These are but a few of literally
hundreds of hematological tests that may be performed on whole blood. Many
of these are extremely sophisticated and complex in the methodology used.
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