Comparison of four direct homogeneous methods for the measurement of low-density lipoprotein cholesterol.
BACKGROUND
The primary lipoprotein risk factor is low-density lipoprotein cholesterol (LDL-C), and medication is targeted at lowering LDL-C values. To clarify the usefulness of direct homogeneous assays for LDL-C measurement, we compared the values obtained by various reagents to those obtained by the Friedewald equation and analyzed different reactivity to IDL/VLDL and LDL.


METHODS
Serum samples were collected from 55 patients with hypercholesterolemia. The LDL-C concentrations were determined by four direct homogeneous assays using reagent A (Kyowa Medex), B (Sekisui Medical), C (Denka Seiken), and D (Sysmex), which are commercially available.


RESULTS
Significant correlation was observed in LDL-C values obtained by the homogeneous assays and the Friedewald equation. However, there were two discrepancies in reagents B and C, respectively. These assays showed 40% and 55% lower LDL-C values than those calculated by the Friedewald equation, respectively. Reactivity to the IDL fraction in reagents B and C was lower than in reagents A and D.


CONCLUSIONS
Direct homogeneous assays for LDL-C are suitable for routine laboratory examination. However, it was shown that attention should be given to the different reactivity to IDL and LDL among reagents in some clinical samples.
Yamada
Koji
K
Division of Laboratory Diagnosis, Sapporo Medical University Hospital, Japan.
Tsuji
Naoki
N
Fujita
Tomoko
T
Tanaka
Maki
M
Kuribayashi
Kageaki
K
Kobayashi
Daisuke
D
Watanabe
Naoki
N
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001774:Blood Chemical Analysis; D002648:Child; D008078:Cholesterol, LDL / Q000097:blood*; D006801:Humans; D006937:Hypercholesterolemia / Q000097:blood / Q000175:diagnosis*; D006951:Hyperlipoproteinemias / Q000097:blood / Q000175:diagnosis*; D008875:Middle Aged; D015203:Reproducibility of Results; D055815:Young Adult
D008078:Cholesterol, LDL