Freeze-thaw and matrix effects in direct high-density lipoprotein cholesterol methods.

Background: There is frequent discussion on the susceptibility of direct high-density lipoprotein cholesterol (HDL-C) methods to matrix effects. In Vitro Diagnostics manufacturers recognize this issue and regularly improve their HDL-C reagent formulations in subsequent generations.

Methods: The 3rd generation direct HDL-C assay from Roche was investigated for matrix effects in comparison to the former generation, a Beckman direct HDL-C method and a conventional phosphotungstate (PTA)/Mg(2+) precipitation method.