Background:
RLP-C is comprised of atherogenic triglyceride- (TG-) rich lipoproteins, commonly defined as the sum of intermediate-density lipoprotein cholesterol (IDL-C) and very low-density lipoprotein cholesterol remnants (VLDL
3
-C). In clinical practice, the VLDL-C/TG ratio is used to diagnose type III dyslipidemia, a primary lipoprotein disorder characterized by high levels of RLP-C.
Methods:
Serum lipids of 556,307 U.S. adults with TG ≥130 mg/dL were analyzed by ultracentrifugation (VAP, Atherotech, Birmingham, AL). We estimated TG content in VLDL (VLDL-TG) as the product of VLDL-C and validated variable TG/VLDL-C factors. Non-VLDL-TG was then calculated as total TG minus VLDL-TG, for which negative values represented the presence of RLP-C. We examined the relationship of non-VLDL-TG to 1000 quantiles of VLDL-C/TG ratio. We defined a VLDL-C/TG ratio cutpoint for presence of RLP-C based on the quantile at which median non-VLDL-TG≤0.
Results:
We found median non-VLDL-TG≤0 at VLDL-C/TG = 0.18
(Figure)
. There were 174,907 adults who did not meet diagnostic criteria for type III dyslipidemia (VLDL-C/TG 0.18 to <0.30), whose levels of RLP-C and non-VLDL-TG levels were 37 (31-46) and -20 (-40 to -8) mg/dL, respectively. A total of 1,550 adults met classical diagnostic criteria for type III dyslipidemia (VLDL-C/TG ≥0.3), whose plasma levels of RLP-C and non-VLDL-TG levels were 80 (67-101) and -187 (-290 to -129) mg/dL, respectively.
Conclusion:
A threshold of VLDL-C/TG ≥0.18 correlates with the accumulation of RLP-C in plasma. If validated in future studies, these findings will improve identification of individuals who are at greater risk for atherosclerotic disease.
Acute hyperinsulinemia and very-low-density and low-density lipoprotein subfractions in obese subjects
