
The hospital
immunohematologist prepares a patient’s blood sample for testing.
|
The clinical pathology specialty laboratories
include hematology, microbiology, immunology, clinical chemistry (and
toxicology), the blood bank (transfusion medicine), and laboratory data
management. In these areas, the pathologist acts as a consultant to the
clinician, defining appropriate tests and interpreting their results. Many
of these tests solidify a clinical diagnosis. After diagnosis, many tests
are performed repeatedly to assess progress of the disease and response to
treatment.
In clinical hematology, for example, pathologists review all abnormal blood
smears. They may also obtain bone marrow samples from patients. In examining
the smears and microscopic sections from these sources, the pathologist may
encounter problems as diverse as the identification of malarial parasites or
other blood-borne organisms, investigation of causes of anemia, detection of
disorders of coagulation, and definitive diagnosis of malignant diseases
such as leukemia.
In most hospital settings the pathologist is in charge of the blood bank and
functions as an immunohematologist, who is in charge of procurement and
processing of blood and blood products. The responsibilities include
monitoring the use of blood within the hospital, tracing the causes of
transfusion reactions, testing for determinants of tissue compatibility that
permit bone marrow and other transplants, and serving as a consultant to
plan appropriate therapy for a wide variety of conditions.
In clinical chemistry, the pathologist supervises the technical staff in
performance of tests to determine the concentration of organic and inorganic
substances and medications in body fluids. For example, the level of glucose
(sugar) in blood or urine is needed to diagnose diabetes and to monitor the
daily insulin dosage. Supervision of the use of instruments and maintenance
of a strict system of quality control are essential to assure accurate
laboratory determinations. Toxicology is often part of the clinical
chemistry service, involving the pathologist in therapeutic drug monitoring
and detection of illicit drugs and poisons. In cases of infection, the
microbiology laboratory identifies the offending organism and tests to
discover which antimicrobials are capable of killing or arresting the growth
of that particular agent (bacteria, viruses, parasites).
Testing for immune reactions and allergies is a growing area of laboratory
activity. Allergic and toxic reactions to foreign materials have long been
recognized, but many recently identified diseases reflect immune responses
to normal body proteins, that are either altered or present in abnormal
locations. Immune functions are also critical in toleration of transplanted
tissues or organs.
Other areas of responsibility of the clinical pathologist are the
development of comprehensive information systems and the maintenance of
quality control and quality assurance procedures. Both are needed to ensure
economical use of the clinical laboratory, to enable the development of new
testing and appropriate utilization of existing services, while maintaining
a high quality of medical care. Pathologists constantly seek ways to achieve
greater accuracy, precision, specificity and sensitivity of laboratory
tests. Information systems are needed to handle the enormous volume of test
information correctly attributed to each individual patient, and provide the
correct ranges of normal values for each test in that laboratory, while
maintaining patient confidentiality. Quality control checks on the accuracy
of test results, whereas quality assurance aims to provide prompt, efficient
collection and rapid availability of test results to the treating physician.
|