MADISON, N.J., June 3 /PRNewswire-FirstCall/ -- Quest DiagnosticsIncorporated (NYSE: DGX) today announced results of a study that demonstratesthat a novel diagnostic testing technique it has developed is the first toprovide direct, accurate and reproducible physical measurement of both thesize and concentration of a broad range of lipoproteins in blood plasma.Results of the study were published in the May 29, 2008, online edition ofClinical Chemistry.
'Our data suggest that this novel ion mobility-based method offersadvantages over other procedures for lipoprotein particle analysis because itboth measures particle size accurately on the basis of physical principles aswell as directly counts the particles present at each size independently ofparticle composition. We believe this approach provides the only directphysical measurement of lipoprotein particle size and concentration for eachlipoprotein subclass, from small HDL to large VLDL,' said Richard E. Reitz,MD, co-lead investigator and acting vice president, Science and Innovation,and medical director, Quest Diagnostics Nichols Institute. 'We look forward tolearning the results of additional research to identify the technique'sclinical utility for risk assessment and treatment in patients withcardiovascular disease and related conditions.'
Lipoprotein particles are fatty substances carried through the bloodstream that affect cardiovascular health. High-density lipoproteins (HDL),referred to as 'good' cholesterol, promote healthy cardiovascular function,but LDL and very-low density lipoproteins (VLDL), or 'bad' cholesterol, maydeposit on the walls of arteries, promoting atherosclerosis and othercardiovascular diseases. Because particles of LDL, intermediate-densitylipoprotein (IDL) and VLDL each contain one apolipoprotein B (ApoB) protein,ApoB concentration may give a better indication of large lipoprotein particleconcentration than measurements of cholesterol concentrations alone(1). TheAmerican Diabetes Association and American College of Cardiology Foundationrecently published a consensus statement that recommends physicians use ApoBmeasurements to guide therapy in individuals with cardiometabolic risk who areon statin therapy(2). Yet, clinically available methods of measuringlipoprotein particle subpopulations are not standardized and generally use analgorithm to indirectly measure lipoprotein particle concentrations.
The objective of the study, conducted by Quest Diagnostics NicholsInstitute, was to describe and validate the ability of the ion mobilitytechnique to directly and accurately measure plasma lipoprotein particles,covering the spectrum of HDL, LDL, IDL and VLDL in healthy adults.Approximately 260 healthy male and female adults who met the NationalCholesterol Education Program's Adult Treatment Panel III guidelines foroptimal plasma lipid and lipoprotein concentrations were recruited toestablish reference distributions for the lipoprotein fractions detected bythe method. Concentrations of total HDL, HDL Large, total LDL, total IDL,total VLDL, and non-HDL particles were determined using the ion mobilitytechnique and correlated with biochemical measurements of calculatedtriglycerides, HDL cholesterol, LDL cholesterol as well as plasma ApoA1 andApoB.
Results showed that the ion mobility technique was very precise inmeasuring LDL particle size, producing a variation of less than one percentover approximately 48 preparations of the same sample. The HDL and LDLconcentrations varied less than 20 percent in these same preparations. Thestudy also found a strong correlation (r=0.92) between the non-HDL (LDL, IDLand VLDL combined) concentration and the plasma concentration of ApoB, thesingle protein present in all non-HDL particles.
