Test panel
Encyclopedia
A test panel is a predetermined group of medical test
s as an aid in the diagnosis
and treatment of disease
.
Test panels (sometimes called profiles) are typically composed of individual laboratory
tests which are related in some way: by the medical condition they are intended to help diagnose (cardiac risk panel), by the specimen type (complete blood count
, CBC), by the tests most frequently requested by users (comprehensive chemistry profile), by the methodology employed in the test (viral panel by polymerase chain reaction), or by the types of components included (urine drug screen
).
s, cost considerations, or compatibility with the testing instruments and methods. Another disadvantage is the fact that approximately 5% of the test results can be expected to fall outside the normal (bell curve
) range for purely statistical reasons. Thus, there is an expectation that the number of abnormal appearing results will increase with the number of tests in the panel (for quantitative
tests such as blood glucose and total protein). For a typical twenty-test panel, there will be, on average, one or more of these apparent abnormal results.
The proportion of such apparently abnormal results may be even higher if the normal ranges printed on the report do not accurately reflect the species
, gender
or age of the patient. It is common for normal ranges for bodily fluid constituents to differ from the general population for very young or old patients, and in some cases (such as hormones) for males versus females. Differences in those parameters between species are more the rule than the exception.
The statistical considerations typically do not apply for qualitative (present or absent) tests, such as drug screens, unless the substance being tested for (e.g. drug) is actually present at a concentration near the cutoff
concentration.
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...
s as an aid in the diagnosis
Diagnosis
Diagnosis is the identification of the nature and cause of anything. Diagnosis is used in many different disciplines with variations in the use of logics, analytics, and experience to determine the cause and effect relationships...
and treatment 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...
.
Test panels (sometimes called profiles) are typically composed of individual laboratory
Laboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
tests which are related in some way: by the medical condition they are intended to help diagnose (cardiac risk panel), by the specimen type (complete blood count
Complete blood count
A complete blood count , also known as full blood count or full blood exam or blood panel, is a test panel requested by a doctor or other medical professional that gives information about the cells in a patient's blood...
, CBC), by the tests most frequently requested by users (comprehensive chemistry profile), by the methodology employed in the test (viral panel by polymerase chain reaction), or by the types of components included (urine drug screen
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...
).
Advantages of diagnostic test panels over individual diagnostic tests
Test panels offer various advantages to laboratories performing the tests (labor efficiency, potential for automation and reduced costs through performing large numbers of the same kinds of tests each day) as well as to end users such as ordering physicians and hospitals (more comprehensive testing, rapid turn-around and lower prices). The presence of several tests responsive to the same clinical condition may also increase the chances of detecting that condition.Disadvantages of test panels
Among the disadvantages of test panels are the inclusion of diagnostically sub-optimal tests based upon commercial availability of test reagentReagent
A reagent is a "substance or compound that is added to a system in order to bring about a chemical reaction, or added to see if a reaction occurs." Although the terms reactant and reagent are often used interchangeably, a reactant is less specifically a "substance that is consumed in the course of...
s, cost considerations, or compatibility with the testing instruments and methods. Another disadvantage is the fact that approximately 5% of the test results can be expected to fall outside the normal (bell curve
Bell curve
Bell curve can refer to:* A Gaussian function, a specific kind of function whose graph is a bell-shaped curve* Normal distribution, whose density function is a Gaussian function...
) range for purely statistical reasons. Thus, there is an expectation that the number of abnormal appearing results will increase with the number of tests in the panel (for quantitative
Quantitative property
A quantitative property is one that exists in a range of magnitudes, and can therefore be measured with a number. Measurements of any particular quantitative property are expressed as a specific quantity, referred to as a unit, multiplied by a number. Examples of physical quantities are distance,...
tests such as blood glucose and total protein). For a typical twenty-test panel, there will be, on average, one or more of these apparent abnormal results.
The proportion of such apparently abnormal results may be even higher if the normal ranges printed on the report do not accurately reflect the species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
, gender
Gender
Gender is a range of characteristics used to distinguish between males and females, particularly in the cases of men and women and the masculine and feminine attributes assigned to them. Depending on the context, the discriminating characteristics vary from sex to social role to gender identity...
or age of the patient. It is common for normal ranges for bodily fluid constituents to differ from the general population for very young or old patients, and in some cases (such as hormones) for males versus females. Differences in those parameters between species are more the rule than the exception.
The statistical considerations typically do not apply for qualitative (present or absent) tests, such as drug screens, unless the substance being tested for (e.g. drug) is actually present at a concentration near the cutoff
Cutoff
In theoretical physics, cutoff is an arbitrary maximal or minimal value of energy, momentum, or length, used in order that objects with larger or smaller values than these physical quantities are ignored in some calculation...
concentration.