REPRODUCIBILITY OF AN ORAL FAT TOLERANCE-TEST

In epidemiological studies concerning cardiovascular risk factors, only fasting values of blood lipids have been considered so far. In order to be able to study the role of elevated postprandial triglycerides as a cardiovascular risk factor, a standardized and reproducible test is a prerequisite. It was the aim of this study to investigate the administration of an oral fat tolerance test in regard to the intra subject reproducibility. Within 12 weeks, 30 male participants, 21 healthy study subjects and 9 patients with coronary heart disease (mean age 48,3 +/- 5,8 years), took 3 oral fat loads each: after an overnight fast of at least 12 hours the participants were given the test meal (3,2 MJ, 49 g fat corresponds-to 58% of total energy). Blood samples for triglyceride analyses were drawn prior to (0) and 1, 2, 3, 4, 5 and 6 hours after the meal. As a means of quantifying the magnitude of postprandial lipemia, the area under the triglyceride curve (>>area under curve<<, AUC) was determined over 6 hours after the meal. The intra subject coefficients of variation of the triglycerides and the AUC were calculated from the three tests for each participant. A coefficient of variation less-than-or-equal-to 20% was considered to indicate good intra subject reproducibility. In the case of small coefficients of variation for the fasting triglyceride values, the reproducibility of the AUC in general was good, whereas strongly diverging fasting triglyceride levels went along with highly variable postprandial triglyceride responses. In 77% of all cases, good reproducibility of the AUC was observed. In those participants who showed good reproducibility of the fasting triglyceride concentration, good reproducibility of the AUC was achieved in 94%. Conclusion: Given comparable fasting triglyceride concentrations, the standardized oral fat tolerance test allows the determination of postprandial triglyceride serum concentrations with good intra subject reproducibility. The method seems to be suitable for the investigation of the role of postprandial triglyceride-rich lipoproteins as a potentially atherogenic risk factor in further clinical studies.