Appendix B: Glossary

accuracy

Closeness of agreement between a measurement result and the true value or the accepted reference value

alternative performance assessment

Quality assessment activities for a test for which proficiency testing is not available or not used for the purpose of verifying the accuracy of the test results

amino acid

Basic structural units of proteins, the measurement of which (in protein and peptide hydrolysates, physiological fluids, and numerous other samples) provide important information for fundamental studies and the diagnosis of many pathological conditions, especially those resulting from inborn errors of metabolism

analyte

Component represented in the name of a measurable quantity

analyte-specific reagent

Antibodies (both polyclonal and monoclonal), specific receptor proteins, ligands, nucleic acid sequences, and similar reagents which, through specific binding or chemical reactions with substances in a specimen, are intended for use in a diagnostic application for identification and quantification of an individual chemical substance or ligand in biological specimens (21 CFR §864.4020[a])

analytical sensitivity

In quantitative testing: the change in response of a measuring system or instrument divided by the corresponding change in the stimulus; in qualitative testing: the test method's ability to obtain positive results in concordance with positive results obtained by the reference method

analytical specificity

Ability of a measurement procedure to measure solely the measurand

biochemical genetic testing

A diverse spectrum of laboratory analyses of metabolites, enzyme activities, and functional assays for evaluation, diagnosis, treatment monitoring, disease management, and assessing a person's risk for carrying a specific disease trait (i.e., carrier status assessment), such as inborn errors of metabolism

clinical sensitivity

The proportion of patients with a well-defined clinical disorder whose test values are positive or exceed a defined decision limit

clinical specificity

The proportion of patients who do not have a specified clinical disorder whose test results are negative or within the defined decision limit

clinical validity

The accuracy with which a test predicts designated intermediate or final clinical outcomes

competency assessment

Evaluation of a person's ability to perform a test, including all aspects of testing, from specimen collection to reporting of results

confirmatory test

A test to prove or disprove the presence of a specific condition identified by screening tests (for newborn screening using dried blood spot specimens, this testing is from a specimen other than the screening specimen)

control material

A device, solution, or lyophilized preparation intended for use in the quality control process to monitor the reliability of a test system and to maintain its performance within established limits

current procedural terminology (CPT) codes

Current procedural terminology code set maintained by the American Medical Association

critical values

Test results that require immediate notification of the clinician for patient evaluation or treatment

cut-off value

Quantitative value of the analyte that is used as the decision point between a positive and a negative result

drift

A slow or systematic change of a metrological characteristic of a measuring instrument or system, such as accuracy, trueness, and precision

genetics

The study of inheritance patterns of specific traits

genome

The complete genetic content of an organism

genotype

The genetic makeup of an organism or group of organisms with reference to a single trait, set of traits, or an entire complex of traits

Health Level Seven
International (HL7)

A standards-development organization that has produced international standards for electronic reporting of laboratory results and orders

in-range result

Newborn screening result that is within the expected range of normal or negative test results established for a particular condition

informed consent

A process by which persons voluntarily confirm their willingness to participate in a particular testing act after having been informed of all aspects of the act that are relevant to the decision to participate in the act

internal control material

A control material that is placed in the same reaction tube as the specimen being analyzed and therefore is subjected to exactly the same internal conditions and external parameters as any analyte present in the tube

International Classification of Diseases (ICD)

The international standard diagnostic classification for the coding of diseases, signs and symptoms, abnormal findings, complaints, social circumstances, and external causes of injury or diseases, as maintained by the World Health Organization

limit of detection (LOD)

The lowest amount of analyte in a sample that can be detected (with stated probability), although the amount might not be quantified as an exact value

limit of quantitation (LOQ)

The lowest concentration at which an analyte can be quantitatively determined with stated acceptable precision and trueness under stated experimental conditions; might be equal to the limit of detection or could be at a higher concentration

measurand

Quantity to be measured

newborn screening

A system that identifies, shortly after birth, infants who are at increased risk for genetic and other congenital conditions so that treatment can begin as soon as possible; need to confirm positive newborn screening results with additional diagnostic testing

nonwaived testing

Test systems, assays, or examinations that have not been determined to be waived testing. Nonwaived testing encompasses moderate- and high-complexity testing for which CLIA regulations provide requirements for laboratory certification, quality systems, performance assessment, and laboratory personnel

out-of-range result

Newborn screening result that is outside the expected range of normal or negative test results established for a particular condition, including carrier results and any need for additional testing

phenotype

The observed biochemical, physiological, and morphological characteristics of an individual as determined by the genotype and the environment in which the genotype is expressed; also, in a more limited sense, the expression of a particular gene or genes

precision

Closeness of agreement between independent test results from the same sample obtained under stipulated conditions, often determined by assessing repeatability and reproducibility

proficiency testing

A program in which multiple samples are periodically sent to members of a group of laboratories for analysis or identification (or both) in which each laboratory's results are compared with those of other laboratories in the group or with an assigned value (or both) and are reported to the participating laboratory and others

repeatability

Closeness of agreement between independent test results for the same measurand under the same conditions

reproducibility

Closeness of agreement between independent test results for the same measurand under changed conditions

qualitative test

A characterization applied to laboratory tests that detect or identify a particular analyte, constituent, or condition

quality assessment

A group of activities to monitor and evaluate the total testing process to help ensure that test results are reliable, improve the testing process, and promote good quality testing practices

quality control

Operational techniques and activities that are used to fulfill requirements for quality; the procedures used to detect and correct errors that occur due to test system failure, adverse environmental conditions, and variance in operator performance, as well as the monitoring of the accuracy and precision of the test performance over time

quality management system (QMS)

Coordinated activities to direct and control an organization with regard to quality

quantitative test

A characterization applied to laboratory tests that provide results expressed in a numerical amount or level (concentration) of an analyte in a sample or specimen

reagent

A substance that produces a chemical or biological reaction with a patient specimen that allows detection or measurement of the analyte for which the test is designed

reference interval

The range of test values expected for a designated population of persons (e.g., 95% of persons that are presumed to be healthy [or normal])

reference material

Material sufficiently homogeneous and stable with respect to one or more specified properties (quantitative or qualitative) that has been established to be fit for its intended use in a measurement process; might be used to calibrate a measurement system, to assess a measurement procedure, to assign values to other materials, and for quality control; can only be used for a single purpose in a given measurement

reportable range of test results

The span of test result values over which the laboratory can establish or verify the accuracy of the instrument or test system measurement response

total testing process

Series of activities or path of workflow for performing testing that can be divided into three major phases: preanalytic, analytic, and postanalytic

trueness

Closeness of agreement between the average of an infinite number of replicate-measured quantity values and a reference quantity value

waived test

A test system, an assay, or an examination that has been found to meet the statutory criteria specified in the Public Health Service Act (§353[d][3]) (12)