Cholestech LDX - Page 48

42 GLOSSARY OF TERMS
Cholestech LDX System Procedure Manual
< TABLE OF CONTENTS
Quantitative – applied to tests that give results expressing the numerical amount of an
analyte in a specimen. This is in contrast to qualitative tests that detect whether a particular
analyte, constituent, or condition is present.
Reactivity – ability of a reagent to produce its proper chemical reaction. Reagents can lose
their reactivity if they are misused, mishandled, or are too old.
Reagent – substance that produces a chemical reaction in a sample that allows an analyte
to be detected and measured.
Reconstitute – to add a diluent to a freeze-dried calibrator, control, or reagent.
Reference Interval – see
Normal Values.
Replicate – to repeat an experiment and/or analysis to check the accuracy of the results.
Each repeat is a replicate (pronounced
rep -li-kit) test or measurement.
Reproducibility – see
Precision .
Result – value obtained by analysis for a particular analyte in a particular sample.
Run (analytical run) – group of measurements by a particular method over a period of time
during which the accuracy and precision of the method are expected to be stable.
Sample – part of a specimen used for an analysis.
Sensitivity – ability of a test to give a positive result for patients who have the disease or
condition they are tested for; measured as the ratio of positive tests to the total number of
tests in those who have the disease; expressed as a percentage.
Serum – liquid part of the blood after it has coagulated and then been spun down in a
centrifuge.
Specificity – ability of a test to give a negative result for patients who do not have the
disease or condition they are tested for; measured as the ratio of negative tests to the total
number of tests in those who do not have the disease or condition; expressed as a
percentage.
Specimen – portion of body fluid (e.g., blood or urine) collected from the patient.
Split-Sample Testing – dividing a sample in half, and testing half in your laboratory and
having the other half tested in another laboratory, and then comparing the results. This is
a technique for testing accuracy.
Stability – ability of a specimen, reagent, or control to maintain a constant concentration of
the analyte. Reagents and controls must be handled and stored properly and used before
their expiration dates to maintain their stability. Specimens must be collected, handled, and
processed properly.
Standard, Primary – reference material of fixed and known chemical composition and
capable of being prepared in essentially pure form. Also: any certified reference material
generally accepted or officially recognized as the unique standard for the assay regardless
of its level of purity of analyte content.