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Leading
Cholesterol Tests may not be accurate in all
situations, Research Team concludes
Newswise, July 2010 — The National
Cholesterol Education Program maintains
guidelines to assess the accuracy of methods
for measuring cholesterol levels in
patients. A recent study published in the
journal Clinical Chemistry found that
seven leading commercial methods produce
results of mixed accuracy when compared to
well-established techniques.
In 2008, there were several different
commercial homogeneous direct measurement
methods for HDL-cholesterol and LDL-cholesterol
determination that were distributed
worldwide under various trade names.
These methods use a wide variety of
surfactants, ionic polymers, and other
components that either selectively prevent
or enable measurements of cholesterol in
specific classes of lipoproteins among the
full range of lipoprotein particles present
in serum.
Despite their advantages, there has been
concern whether direct lipoprotein
cholesterol methods generate equivalent
values as older more skill-demanding methods
and to the established reference measurement
procedures for HDL-C and LDL-C used as the
basis for clinical guidelines.
A research team led by W. Greg Miller of
Virginia Commonwealth University evaluated
seven commercially available direct
measurement reagents for quantifying HDL-C
and LDL-C. The team examined 175 patients in
all—37 with no known disease and 138 with
known cardiovascular disease and other
conditions such as dyslipidemia—and compared
the results to those obtained by reference
measurement procedures.
They evaluated trueness, accuracy for
individual samples, imprecision, and
specificity for HDL and LDL lipoproteins,
thus providing a comprehensive assessment of
the analytical performance of the current
direct lipoprotein methods.
“In the non-diseased individuals, six of
eight HDL-C and five of eight LDL-C direct
methods met the National Cholesterol
Education Program [guidelines],” said
research team member Elizabeth T. Leary,
PhD, Chief Scientific Officer at Pacific
Biomarkers, Inc. “However, all the methods
failed to meet the NCEP’s goals for diseased
individuals, because of compromised
specificity toward abnormal proteins.”
Dr. Leary continued, “Homogeneous methods
suffer from non-specificity in unusual
samples, i.e., lipoproteins which are
structurally or compositionally altered as
in certain diseases (e.g. diabetes), unusual
phenotypes or after certain drug treatments.
"Each homogeneous method is based on a
different separation principle and some
homogeneous methods may be better than
others. As observed in the study, all
methods are more variable in diseased
samples. The fact is that no method can be
‘correct’ all of the time including the
‘reference methods’. It all depends on the
definition of truth. The bottom line is that
one needs to know the assays, use them
appropriately and interpret the data
accordingly.”
For more information, please log on to
www.pacbio.com
