Comparison between Fractional Turnover Rate of Endogenous Plasma Triglycerides and of Intralipid® (Intravenous Fat Tolerance Test) in Man*

Abstract. The validity of the intravenous fat tolerance test (IVFTT) as a tracer for the fractional turnover rate of endogenous plasma triglycerides (TG) has been studied in 32 fasting men with either normal or elevated plasma TG concentrations. The endogenous plasma TG turnover was determined by sampling arterial and hepatic vein blood, determination of splanchnic net secretion of plasma TG and calculation of fractional TG turnover rate. Later the fractional elimination rate of exogenous TG was determined following a single IV injection of Intralipid® (IVFTT). The TG fractional removal rate constants derived from these two tests were significantly correlated (r = 0.6-0.7) but IVFTT gave higher absolute values. A statistical evaluation showed that the error for the determination of the fractional turnover rate of endogenous TG and the IVFTT were about 30–50% and 10% respectively. It is probable that the correlation would have been still better if the error for the estimation of endogenous plasma TG turnover had been lower. A significant negative correlation was found between very low density lipoprotein-TG concentration and fractional removal rate of both endogenous and exogenous plasma TG (r = ?0.7–0.8).