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Medical test
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A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:
A drug test can be a specific medical test to acertain the presence of a certain drug in the body (for example, in drug addicts).
medical tests are parts of a simple physical examination which require only simple tools in the hands of a skilled practitioner, and can be performed in an office environment.
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Encyclopedia
A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:
- to diagnose diseases
- to measure the progress or recovery from disease
- to confirm that a person is free from disease
A drug test can be a specific medical test to acertain the presence of a certain drug in the body (for example, in drug addicts).
Overview
Some medical tests are parts of a simple physical examination which require only simple tools in the hands of a skilled practitioner, and can be performed in an office environment. Some other tests require elaborate equipment used by medical technologists or the use of a sterile operating theatre environment.
Some tests require samples of tissue or body fluids to be sent off to a pathology lab for further analysis. Some simple chemical tests, such as urine pH, can be measured directly in the doctor's office.
Most medical tests are conducted on the living; however, some of these tests can also be carried out on a dead person as part of an autopsy.
The validity of diagnostic test results produced in each laboratory is entirely dependent on the measures employed before, during, and after each assay. Consistency in the production of good results requires an overall program that includes quality assurance, quality control, and quality assessment.
Medical tests can be classified into three categories:
Test Characteristics
- Accuracy of a laboratory test is its correspondence with the true value. Accuracy is maximized by calibrating laboratory equipment with reference material and by participation in external quality control programs.
- Precision is a measure of tests reproducibility when repeated on the same sample. An imprecise test is one that yield widely varying results on repeated measurement. The precision is monitored in laboratory by using control material.
Properties
The result of a test may be positive or negative: this has nothing to do with a bad prognosis, but rather means that the test worked or not, and a certain parameter that was evaluated was present or not. For example, a negative screening test for breast cancer means that no sign of breast cancer could be found (which is in fact very positive for the patient).
Bayesian probability and performance metrics
Other characteristics of tests include:
Types of medical tests
Consulting room tests
More invasive examinations requiring sterile procedures
Requiring laboratory analysis
Requiring microscopy
Requiring elaborate medical equipment
Psychological effects of diagnostic tests
Medical tests can have value when results are abnormal by explaining to a patient the cause of their symptoms. In addition, normal test results can have value by reassuring patients that serious illness is not present and even reduce the rates of subsequent symptoms. Understanding the meaning of a normal test in advance of learning the test results may also reduce the rates of subsequent symptoms.
Lack of adequate education about the meaning of test results (especially relevant to tests that may have incidental and unimportant findings) may cause an increase in symptoms. In addition, the possible benefits must be weighed against the costs of unnecessary tests and resulting unnecessary follow-up and possibly even unnecessary treatment of incidental findings.
See also
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