Abstract 601: Identifying Chylomicrons Using the Triglyceride/Total Cholesterol ratio (TG/TC) and non-Very Low-Density Lipoprotein Triglyceride (non-VLDL TG): The Very Large Database of Lipids Study (VLDL-7B)

Abstract

Background: Chylomicrons are triglyceride- (TG-) rich lipoproteins. Chylomicronemia is usually diagnosed on the basis of a very high TG level or an elevated TG/TC ratio. Methods: We examined 1,350,908 U.S. adults from the Very Large Database of Lipids whose lipids were analyzed by ultracentrifugation (VAP, Atherotech, Birmingham, AL). We estimated the TG content of very low-density lipoprotein (VLDL-TG) as the product of VLDL-C and a validated adjustable Friedewald-like factor. We estimated non-VLDL TG as total TG - (VLDL-TG). We examined the association of non-VLDL TG to TG/TC, proposing new diagnostic criteria for chylomicronemia based on non-VLDL TG and TG/TC. The intercept point was estimated through the intersection of the 95 th percentile line for non-VLDL TG (32 mg/dL) by projecting a regression line fitted for those with non-VLDL TG ≥500 mg/dL, in which there is a visually linear relationship between Non-VLDL TG and Ln (TG/TC) (Figure). Results: Using a conventional threshold of TG/TC ≥10, there were 427 adults (0.03%) with chylomicron excess. TG and non-VLDL TG levels were 2836 (2074 to 4297) and 1814 (1201 to 2851) mg/dL at TG/TC ≥10, respectively. We identified a new threshold from the intercept point in the plot at approximately TG/TC = 5.2. Using TG/TC ≥5.2 and non-VLDL TG ≥32 mg/dL, 2139 (0.16%) adults were identified as having chylomicron excess. In these individuals, TG and non-VLDL TG levels were 1394 (1100 to 2014) and 515 (301 to 932) mg/dL, respectively. Conclusion: The threshold of TG/TC ≥5.2 with or without non-VLDL TG ≥32 mg/dL may better identify the chylomicronemic patient. If validated in future studies, these findings will improve diagnosis of chylomicronemia.