Gas chromatographic evaluation of plasma triglyceride composition in hyperlipidemia

Abstract

The molecular distribution of human plasma triglycerides was studied by gas—liquid chromatography. Triglycerides of the total plasma lipids are separated into fractions according to molecular weight. Individual fractions consist of molecules containing constant numbers of carbon atoms in the acyl chains. The carbon number serves to designate the fraction. In normal plasma it is possible to separate plasma triglycerides into four main fractions: C 48, C 50, C 52, and C 54. The reference group consists of 199 apparently healthy subjects (93 men, 106 women) and is stratified according to age. Triglyceride values were adjusted to age and sex. Parameters of triglyceride fractions C 48-C 56 were calculated after arcsin transformation of percentage values. The group of hypertriglyceridemic subjects totals 113 (56 men, 57 women). Their adjusted triglyceride values exceed the 95 percentile of the reference group values. Analysis of the triglyceride fractions gives the following results: 1. In more than a quarter of the hypertriglyceridemic patients a different molecular distribution was demonstrated. Mostly it was fraction C 56 that was increased in proportion. 2. There seems not to be an anomaly of triglyceride molecular distribution associated with any type of hyperlipoproteinemia. Nevertheless, in a family with type III hyperlipoproteinemia we observed a constant increase of C 56 and higher fractions. Fraction C 56 and higher molecular weight fractions contain one or more twenty-carbon or longer fatty acids chains. We conclude that hypertriglyceridemia in about one quarter of cases is associated with a disorder of the metabolism of triglyceride molecules containing C 20 or longer fatty acid chains.