A third of nonfasting plasma cholesterol is in remnant lipoproteins: Lipoprotein subclass profiling in 9293 individuals.

BACKGROUND AND AIMS

Increased concentrations of calculated remnant cholesterol in triglyceride-rich lipoproteins are observationally and genetically, causally associated with increased risk of ischemic heart disease; however, when measured directly, the fraction of plasma cholesterol present in remnant particles is unclear. We tested the hypothesis that a major fraction of plasma cholesterol is present in remnant lipoproteins in individuals in the general population.

METHODS

We examined 9293 individuals from the Copenhagen General Population Study using nuclear magnetic resonance spectroscopy measurements of total cholesterol, free- and esterified cholesterol, triglycerides, phospholipids, and particle concentration. Fourteen subclasses of decreasing size and their lipid constituents were analysed: six subclasses were very low-density lipoprotein (VLDL), one intermediate-density lipoprotein (IDL), three low-density lipoprotein (LDL), and four subclasses were high-density lipoprotein (HDL). Remnant lipoproteins were VLDL and IDL combined.

RESULTS

Mean nonfasting cholesterol concentration was 1.84 mmol/L (72 mg/dL) for remnants, 2.01 mmol/L (78 mg/dL) for LDL, and 1.83 mmol/L (71 mg/dL) for HDL, equivalent to remnants containing 32% of plasma total cholesterol. Of 14 lipoprotein subclasses, large LDL and IDL were the ones containing most of plasma cholesterol. The plasma concentration of remnant cholesterol was from ∼1.4 mmol/L (54 mg/dL) at age 20 to ∼1.9 mmol/L (74 mg/dL) at age 60. Corresponding values for LDL cholesterol were from ∼1.5 mmol/L (58 mg/dL) to ∼2.1 mmol/L (81 mg/dL).

CONCLUSIONS

Using direct measurements, one third of total cholesterol in plasma was present in remnant lipoproteins, that is, in the triglyceride-rich lipoproteins IDL and VLDL.