40 GLOSSARY OF TERMS
Cholestech LDX System Procedure Manual
< TABLE OF CONTENTS
Gravimetry – measurement of a substance by determining its weight or specific gravity.
Hematoma – mass of blood, usually clotted, under the skin in an organ, space, or tissue
caused by a break in the wall of a blood vessel.
Hematocrit – (also called
packed cell volume
) volume percentage of erythrocytes (red blood
cells) in whole blood.
Hemolysis – (adjective
hemolytic
) breakdown of red blood cells in serum or plasma, freeing
the hemoglobin from the cells. When this happens, the serum or plasma becomes reddish.
Hemolysis interferes with some laboratory tests.
Beta hemolysis
is the production of a clear
zone surrounding a bacterial colony on blood-agar medium, which is characteristic of
certain pathogenic bacteria such as Group A
Streptococcus
.
Icterus – (adjective icteric) condition in which there is too much bilirubin in the blood;
jaundice. An icteric serum sample looks dark yellow (it may even look greenish). An icteric
sample may produce erroneous test results.
Immunoassay – diagnostic test that uses a specific antibody or antigen to detect the
presence of an analyte.
Inaccuracy – see
Bias.
In Control – in a testing procedure when the results from a control sample or series of
control samples are within the acceptable control range.
Infectious Agent – any microorganism that can invade body tissue and multiply, causing
infection.
In Vitro
– Latin for “in glass,” used to describe diagnostic tests that analyze processes
occuring inside the body (
in vivo
) from samples of body fluids in glass (test tubes) or other
controlled artificial environments.
Levey-Jennings Chart – quality control chart; a graph or table that shows results of control
tests over a period of time; used in a quality control program.
Linearity – measure of the range (the
linear range
) of concentration of an analyte over
which a measure or test produces consistent (
i.e.,
linear, straight line) and accurate results.
Lipemia – (adjective
lipemic
) condition of too much fat or lipids in the blood. A lipemic
serum sample looks milky and turbid, and may produce erroneous results.
Lyophilized – freeze-dried; a lyophilized calibrator, control, or reagent has been specially
dried to make its analytes more stable. It must be refrigerated to maintain its stability, and is
reconstituted by adding an appropriate diluent.
Matrix – physical and chemical properties that describe a fluid. Often used to describe the
effect of differences seen when lyophilized (freeze-dried) samples, such as control material,
behave differently than patient specimens when analyzed.
Mean – average of the numerical results obtained from a series of analyses.
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