1H NMR-based absolute quantitation of human lipoproteins and their lipid contents directly from plasma.

A new method is presented for absolute quantitation of lipid and protein contents of human lipoproteins directly from plasma. The method enables complete lipoprotein lipid profiles to be obtained in a total time of less than one hour. Absolute concentrations of triglycerides, phospholipids, total cholesterol, free cholesterol, esterified cholesterol, total proteins, and total masses can be estimated for the very low density (VLDL) and low density (LDL) lipoprotein fractions. For the high density lipoprotein (HDL) fraction all components except triglycerides can be quantitated. The method is a combination of 1H NMR spectroscopy and a sophisticated lineshape fitting analysis technique. In this paper we present the calibration of the method using 15 plasma samples followed by a double-blind test of 51 plasma samples from 43 individuals. In total, 66 plasma samples were analyzed. Comparison of the 1H NMR-based results with the data of the biochemical assays showed excellent agreement; the correlation coefficient for VLDL triglycerides was 0.98, for LDL cholesterol 0.88, and for HDL cholesterol 0.93. This method can be directly integrated to many kinds of biomedical NMR studies to offer additional biochemically important quantitative lipoprotein information, the measurement of which is usually too laborious by conventional biochemical methods and too high-priced to be adapted into the study protocols. Moreover, the method also has considerable potential to be developed for a routine clinical assay.