Validation of a novel homogeneous assay for of HDL3-C measurement

Low serum concentration of high density lipoprotein2 cholesterol (HDL2-C) is associated with increased risk of cardiovascular events. HDL2-C is calculated indirectly by subtracting high density lipoprotein3 cholesterol (HDL3-C) from total high density lipoprotein cholesterol (HDL-C). However, the special equipment and long assay times required for HDL3-C measurement have hindered the use of HDL2-C clinically. Here, we report the validation of a simple and rapid homogeneous assay for HDL3-C that is adaptable to clinical chemistry analyzers.

Method comparison based on 2740 serum specimens spanning the physiological range of HDL3-C was analyzed in singlicate to evaluate and validate a new homogeneous assay from Denka Seiken against the conventional dextran sulfate precipitation method. This study was performed over five days. Serum pools were prepared for the analysis of precision over 5 days (5 measurements per day), linearity, and interference (hemoglobin, bilirubin, and triglycerides) evaluation.

The homogeneous method had good within-run precision at concentrations of 24, 36, and 46 mg/dl, yielding standard deviations (SD) of 0.2 (0.9%) 0.4 (1.2%), and 0.5 (1.1%), respectively. Between-day precision, performed over 5 days using the same serum pools, yielded SD of 0.3 (1.4%), 1.0 (2.8%), and 0.9 (2.0%), respectively. The assay was linear from 1 to 100 mg/dl and correlated very well with the dextran sulfate precipitation method. There was no interference from hemoglobin up to 500 mg/dl, bilirubin up to 25 mg/dl, or triglycerides up to 1500 mg/dl.

This homogeneous HDL3-C assay quantitatively measures HDL3-C in serum samples and has excellent precision, and can be implemented on an automated chemistry analyzer, thereby facilitating rapid measurement (~10 min) of a large number of samples in a standard clinical laboratory without the need for additional expensive equipment, laboratory space, or specially-trained staff.