LDL Particle Concentration NMR, Plasma
Method Description Describes how the test is performed and provides a method-specific reference
LDL particle concentrations are measured using an automated nuclear magnetic resonance (NMR) spectrometer. Lipoproteins are analyzed by the NMR according to the spectral signals produced by the terminal methyl groups contained within the lipid particles. The number of methyl groups present on triglycerides, cholesterol, cholesteryl esters, and phospholipids is consistent for particles at a given size, allowing for translation into particle concentration. Individual subclasses are derived using the measured amplitude of the NMR signal along with a deconvolution algorithm. The total LDL-P concentration is the sum of all LDL particle subfractions/sizes and is inclusive of IDL and Lp(a). NMR lipoprotein analyses have been evaluated against other existing methods of lipoprotein subclass methodologies; however, there are no standardization programs targeted towards these analytes.(Otvos JD: Measurement of lipoprotein subclass profiles by nuclear magnetic resonance spectroscopy. Clin Lab 2002;48:171-180; Jeyarajah EJ, Cromwell WC, Otvos JD: Lipoprotein particle analysis by nuclear magnetic resonance spectroscopy. Clin Lab Med 2006;26:847-870; Freedman DS, Otvos JD, Jeyarajah EJ, et al: Sex and age differences in lipoprotein subclasses measured by nuclear magnetic resonance spectroscopy: the Framingham Study. Clin Chem 2004;50:1189-1200)
Day(s) and Time(s) Test Performed Outlines the days and times the test is performed. This field reflects the day and time the sample must be in the testing laboratory to begin the testing process and includes any specimen preparation and processing time required before the test is performed. Some tests are listed as continuously performed, which means assays are performed several times during the day.
Monday through Friday; Continuous
Analytic Time Defines the amount of time it takes the laboratory to setup and perform the test. This is defined in number of days. The shortest interval of time expressed is "same day/1 day," which means the results may be available the same day that the sample is received in the testing laboratory. One day means results are available 1 day after the sample is received in the laboratory.
Same day/5 days
Maximum Laboratory Time Defines the maximum time from specimen receipt at Mayo Medical Laboratories until the release of the test result
Specimen Retention Time Outlines the length of time after testing that a specimen is kept in the laboratory before it is discarded
Performing Laboratory Location The location of the laboratory that performs the test