Further methodological studies on the intravenous fat tolerance with Intralipid emulsion

Factors affecting the reproducibility of the intravenous fat tolerance test (IVFTT) with the Intralipid emulsion have been studied in man. Temperature variations of the emulsion at the time of injection did not affect the fractional removal rate k2. Plasma samples could be treated at room temperature without affecting the k2 value. Linear k2 slopes were obtained also in pronounced hypertriglyceridaemia, which suggests that the test can be applied in subjects with wide ranges of serum triglyceride (TG) concentrations. In subjects with a wide range of serum lipids but at steady state with regard to lipid metabolism, the IVFTT was found to be highly reproducible when repeated with intervals of up to 6 months. Furthermore, the turnover of serum TG, determined as the product of the fractional removal rate and the serum TG concentration, was constant. Most Intralipid batches gave identical k2 results. In some comparisons, batches were found which gave k2 curves significantly different from the standard batches. It is recommended that the IVFTT is carried out only with Intralipid emulsions that have been standardized in this respect.