Medical test
Encyclopedia
A diagnostic test is any kind of medical test
performed to aid in the diagnosis
or detection of disease
. For example:
Companion diagnostics have also been developed to preselect patients for specific treatments based on their own biology. Such targeted therapy holds great promise in the treatment of diseases such as cancer
.
A drug test
can be a specific medical test to ascertain the presence of a certain drug in the body (for example, in drug addicts).
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 technologist
s 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 diagnostic 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:
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.
Interpretation of diagnostic tests should always take sources of inaccuracy and imprecision into account. Sources of inaccuracy and imprecision of diagnostic tests may broadly be categorized as:
Medical test
A diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:* to diagnose diseases, and preferably sub-classify it regarding, for example, severity and treatability...
performed to aid in the diagnosis
Medical diagnosis
Medical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
or detection of disease
Disease
A disease is an abnormal condition affecting the body of an organism. It is often construed to be a medical condition associated with specific symptoms and signs. It may be caused by external factors, such as infectious disease, or it may be caused by internal dysfunctions, such as autoimmune...
. For example:
- to diagnoseMedical diagnosisMedical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
diseases, and preferably sub-classify it regarding, for example, severity and treatability - to confirm that a person is free from disease
Companion diagnostics have also been developed to preselect patients for specific treatments based on their own biology. Such targeted therapy holds great promise in the treatment of diseases such as cancer
Cancer
Cancer , known medically as a malignant neoplasm, is a large group of different diseases, all involving unregulated cell growth. In cancer, cells divide and grow uncontrollably, forming malignant tumors, and invade nearby parts of the body. The cancer may also spread to more distant parts of the...
.
A drug test
Drug test
A drug test is a technical analysis of a biological specimen – for example urine, hair, blood, sweat, or oral fluid / saliva – to determine the presence or absence of specified parent drugs or their metabolites...
can be a specific medical test to ascertain the presence of a certain drug in the body (for example, in drug addicts).
Overview
Some diagnostic tests are parts of a simple physical examinationPhysical examination
Physical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
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 technologist
Medical technologist
A Medical Laboratory Scientist is a healthcare professional who performs chemical, hematological, immunologic, microscopic, and bacteriological diagnostic analyses on body fluids such as blood, urine, sputum, stool, cerebrospinal fluid , peritoneal fluid, pericardial fluid, and synovial...
s 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
Medical laboratory
A medical laboratory or clinical laboratory is a laboratory where tests are done on clinical specimens in order to get information about the health of a patient as pertaining to the diagnosis, treatment, and prevention of disease.-Departments:...
for further analysis. Some simple chemical tests, such as urine
Urine
Urine is a typically sterile liquid by-product of the body that is secreted by the kidneys through a process called urination and excreted through the urethra. Cellular metabolism generates numerous by-products, many rich in nitrogen, that require elimination from the bloodstream...
pH
PH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
, can be measured directly in the doctor's office.
Most diagnostic 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
Autopsy
An autopsy—also known as a post-mortem examination, necropsy , autopsia cadaverum, or obduction—is a highly specialized surgical procedure that consists of a thorough examination of a corpse to determine the cause and manner of death and to evaluate any disease or injury that may be present...
.
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:
- invasive
- minimally invasive
- non-invasive
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.
Interpretation
The aim of a diagnostic test is to have an answer whether a condition is present or not in the test target, or at least contributing in estimating a post-test probability of it.Interpretation of diagnostic tests should always take sources of inaccuracy and imprecision into account. Sources of inaccuracy and imprecision of diagnostic tests may broadly be categorized as:
- Physical sources within the diagnostic test taking itself
- Interpretational sources of the resultant data in relation to the target condition. Such sources include conversion of continuous values to binary ones (creating artificially binary values), such as designating a blood test for prostate specific antigenProstate specific antigenProstate-specific antigen also known as gamma-seminoprotein or kallikrein-3 is a glycoprotein that in humans is encoded by the KLK3 gene. KLK3 is a member of the kallikrein-related peptidase family that are secreted by the epithelial cells of the prostate gland...
as "positive" when having reached a certain cutoff value, which is generally less accurate than considering the value itself.
See also
- Medical testMedical testA diagnostic test is any kind of medical test performed to aid in the diagnosis or detection of disease. For example:* to diagnose diseases, and preferably sub-classify it regarding, for example, severity and treatability...
- Medical diagnosisMedical diagnosisMedical diagnosis refers both to the process of attempting to determine or identify a possible disease or disorder , and to the opinion reached by this process...
- Medical recordMedical recordThe terms medical record, health record, and medical chart are used somewhat interchangeably to describe the systematic documentation of a single patient's medical history and care across time within one particular health care provider's jurisdiction....
- Nailbed assessmentNailbed assessment-Nail bed Nursing Assessment:Fingernails and Toenails provide important information about a patient's health. A visual inspection of an individuals' nail beds...
- Physical examinationPhysical examinationPhysical examination or clinical examination is the process by which a doctor investigates the body of a patient for signs of disease. It generally follows the taking of the medical history — an account of the symptoms as experienced by the patient...
- Gold standard (test)Gold standard (test)In medicine and statistics, gold standard test refers to a diagnostic test or benchmark that is the best available under reasonable conditions. It does not have to be necessarily the best possible test for the condition in absolute terms...