Randox develops highly accurate method to determine LDL cholesterol
11 January 2012
Crumlin, UK. Randox have developed a highly specific and
accurate direct method to overcome issues with traditional methods of
LDL cholesterol determination.
Elevated levels of LDL cholesterol constitute a major risk factor
for coronary heart disease. Treatment decisions are often based on
LDL levels as such accurate determination is paramount.
Many laboratories do not analyse LDL directly but simply
calculate LDL using the Friedewald equation. The Friedewald equation
enables the estimation of LDL cholesterol when triglyceride and HDL
levels are known however it has known limitations and is only
accurate when triglyceride levels are below 400mg/dl, chylomicrons
are absent and the sample does not contain beta-VLDL.
Research shows at triglyceride levels more than 250mg/dl over 20%
of samples are mis-estimated using Friedewald calculation. Due to
these limitations the National Cholesterol Education Programme
(NCEP) recommend the direct measurement of LDL cholesterol.
The preferred ultracentrifugation method for LDL determination
allows for the selection of specific types of lipoproteins based on
their density. Although highly accurate ultracentrifugation methods
are not routinely used as they are time and labour consuming,
difficult to automate and require specialised equipment which many
laboratories do not have.
To overcome the limitations of the Friedewald equation and the
ultracentrifugation method, Randox have developed a clearance method
for the direct measurement of LDL cholesterol. Unlike most
commercially available direct LDL assays the Randox advanced reagent
formulation enables the rapid clearance of turbidity resulting in
reduced interference from bilirubin and triglycerides. The assay
works by removing all non-LDL components in the first step of the
reaction enabling LDL cholesterol to be accurately and specifically
measured in the second step.
Despite being based on the clearance method the detergents and
buffering systems used in most other direct assays vary leading to
significant differences in assay performance.
Further benefits of the Randox direct clearance LDL assay include
excellent correlation to the ultracentrifugation method with a
correlation coefficient of 0.99, the availability of fully automated
applications for a wide range of clinical analysers, excellent
onboard stability and reduced labour, time and consumable costs.
Furthermore all reagents are liquid ready to use eliminating the
risk of reconstitution errors, potential contamination and bottle to