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Published on: October 12, 2017
Comparison of four direct homogeneous methods for the measurement of low-density lipoprotein cholesterol
Koji Yamada1, Naoki Tsuji, Tomoko Fujita
1Division of Laboratory Diagnosis, Sapporo Medical University Hospital, Japan.
Insights
Direct homogeneous assays for low-density lipoprotein cholesterol (LDL-C) are suitable for lab testing. However, variations in reagent reactivity to IDL/VLDL and LDL require careful consideration in clinical practice.
Area of Science:
- Clinical Chemistry
- Lipid Metabolism
- Diagnostic Assays
Background:
- Low-density lipoprotein cholesterol (LDL-C) is a primary lipoprotein risk factor for cardiovascular disease.
- Medications primarily aim to reduce LDL-C levels.
- Evaluating the accuracy of direct homogeneous LDL-C assays against the Friedewald equation is crucial.
Purpose of the Study:
- To assess the clinical utility of direct homogeneous assays for LDL-C measurement.
- To compare LDL-C values from four commercial reagents with the Friedewald equation.
- To analyze the differential reactivity of these assays towards intermediate-density lipoprotein (IDL)/very-low-density lipoprotein (VLDL) and LDL particles.
Main Methods:
- Serum samples from 55 hypercholesterolemic patients were analyzed.
- LDL-C concentrations were determined using four distinct direct homogeneous assay reagents (A, B, C, D).
- Results were compared with LDL-C values calculated using the Friedewald equation.
Main Results:
- A significant correlation was found between LDL-C values from homogeneous assays and the Friedewald equation.
- Reagents B and C showed substantial discrepancies, yielding 40% and 55% lower LDL-C values, respectively.
- Lower reactivity to the IDL fraction was observed with reagents B and C compared to reagents A and D.
Conclusions:
- Direct homogeneous LDL-C assays are generally suitable for routine laboratory diagnostics.
- Clinicians should be aware of inter-reagent variability in reactivity to IDL and LDL fractions.
- Careful selection of reagents is necessary for accurate LDL-C assessment in specific patient populations.
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.
