Valuable information about the way the body is functioning and the state of
health can be obtained by taking samples (for example blood, tissues or urine) from the
body and performing tests on these samples in a medical laboratory. The tests performed
include microscopic examination of cells and structures, measuring the concentrations of
various chemical and biochemical components using automated analysers, counting cells,
measuring physical properties and making biological cultures.
Most medical laboratory tests are made in connection with an infection, an
accident or to follow the treatment that is given. One of the first steps after a medical
examination is often to take a blood sample and to request the medical laboratory to carry
out a number of physical and biochemical tests. The results of the tests are used in
disease management to assist the doctor (in the hospital or in general practice) in making
the best decisions about treatment.
Laboratory tests are also widely used in prevention of disease, for example, to
screen populations or groups for hidden disease or risk factors and are being used
increasingly in health management to check personal health status.
The results of these tests are a unique source of objective information about
the person's state of health or disease.
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Anyone who has visited a medical laboratory will know that it is a "high
tech" world, with automated machines testing hundreds of samples a day. Many hundreds
of sample components can be measured, but usually between two and ten are measured for
each sample. Some tests (for example biological cultures) take time, but others can be
carried out rapidly if there is an emergency.
The results are sent to the doctor in the form of a laboratory report for each
sample that gives the results in comparison with normal values. In many cases the doctor
will discuss the results with and request additional information from specialists in the
medical laboratory.
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Among health professionals laboratory tests are called in vitro diagnostic (or
IVD) tests because they were traditionally performed in a test tube (in vitro means
literally "in glass") and because they are mostly used to help determine (or
diagnose) what is wrong with a patient.
In vitro is also used in contrast to in vivo, which means "in life" .
Unlike many other medical diagnostic procedures which physically effect the patient, in
vitro tests are performed on samples and do not come into contact with patients. For this
reason in vitro diagnostics are generally considered to have a much smaller risk for
patients than other medical devices.
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Most laboratory tests are used in the management of disease. Although there are
a number of tests that could be performed as part of health management, for example
testing blood cholesterol or lipoprotein levels as predictor of heart disease, usually
healthy people do not ask for such tests. Factors which play a part are the inconvenience
of going to a medical laboratory or to the doctor's surgery to have a test performed and
waiting for the result.
Laboratory tests can be developed in formats that are suitable for public use
and give rapid results. When such self-tests are available (for example pregnancy tests)
they are generally well accepted and widely used. In general the Public understand that
tests can be performed incorrectly, can require additional testing before the result is
certain and that the doctor may need to be consulted. Even tests requiring blood sampling
(for example, blood glucose tests for diabetics) can be developed into user-friendly
formats.
Unfortunately, there is little acceptance for self testing among health
authorities and many health professionals. There are a number of possible reasons for
this. For example, there is a fear that such tests will increase the demand for health
care and therefore its cost. Health authorities in many European countries prohibit HIV
selftests, because they can be performed privately. They are convinced that a test
indicating infection with the virus (perhaps a false result) could result in suicide,
unless medical counselling is given.
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The industry produces analytical instruments and the reagents and accessories
which are used to do in vitro diagnostic tests. Reagents are highly specific biological or
chemical substances in special solutions that are able to combine with target substances
in the samples and give a product that can be measured or seen. The analytical instruments
are the various machines and equipment that are used to bring samples and reagents
together or to measure other parameters in the samples.
The in vitro diagnostics industry also produces a number of accessory products
like software programs to run the instruments, control solutions to check the performance
of the systems in addition to supplying information and training for users.
Together the reagents, the instruments and the accessories are referred to as in
vitro diagnostic "systems".
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In vitro diagnostic products and systems are used in medical practice for a
variety of applications. As the name implies they are mainly used to determine (or
diagnose) what is wrong with a patient. In addition, they have many other uses in the
management of disease. For example, to make sure that the treatment given is having the
right effect, to ensure a proper match in blood transfusion and organ transplantation, to
control that the levels of medicine given are providing the right amount in the
circulation. They are used to detect infection and the presence of micro-organisms
(bacteria, viruses and fungal diseases). They are used to screen populations at risk for
hidden diseases that do not give symptoms.
Similar products can also be used in health management. Pregnancy tests fall
into this category. However, there are many other tests that could be used more widely to
check individual health status. Many of these are discussed in the press and for example
in women's journals (often it is the women of the family who are most health conscious).
Many similar or identical products are also used for applications other than the
management of individual health and disease.
For example similar tests are used for the detection of viruses in pooled blood
for plasma protein production in the medicinal industry, as a part of the production
process. The tests are used in veterinary medicine, for pet animals, for farm animals.
They are used widely in forensic medicine
Non medical applications include environmental control (for example the control
of water quality), for detection of contamination of food and raw materials (for example
for traces of penicillin in milk), for detection of micro-organisms in the production of
food and medicine
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There is nothing new about genetic testing itself, but the technologies now
available will allow a more reliable estimation of the risks of disease that individuals
have because of their genetic make up. The ethical debate centers on whether we should use
the tests and under what circumstances.
There are numerous examples of use of genetic information that is accepted and
supported widely.
Insurance companies have always had an interest in the family history and other
simple indicators (for example weight in relation to height and blood pressure) in order
to estimate the risk of invalidity or premature death that a new applicant for insurance
may have.
It is common in Southern Europe for families to be tested for sickle cell anemia
as part of genetic counselling before marriage
EDMA has developed a position
paper on the ethical aspects of genetic testing.
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