Ratio of remnant-like particle-cholesterol to serum total triglycerides is an effective alternative to ultracentrifugal and electrophoretic methods in the diagnosis of familial type III hyperlipoproteinemia.

Background: Familial type III hyperlipoproteinemia (HLP) is characterized by the presence of β-migrating VLDL (β-VLDL) and increased risk of cardiovascular disease. Assessment of plasma β-VLDL is achieved by measuring the ratio of VLDL-cholesterol (VLDL-C) to total plasma triglycerides (TGs) or by detecting β-VLDL in total VLDL. The objective of this study was to compare the clinical utility of the ratio of remnant-like particle-cholesterol (RLP-C) to total TGs with that of the current methods for diagnosing type III HLP. Methods: Detection of β-VLDL by electrophoresis of VLDL was used to define type III HLP. Twenty-eight patients with type III HLP and 43 subjects lacking β-VLDL were investigated. Fasting TG concentrations were >2.26 mmol/L in all subjects. Subjects were separated into three groups: group 1, serum total cholesterol ≤5.18 mmol/L (n = 11); group 2, total cholesterol >5.18 mmol/L and TGs between 2.26 and 9.04 mmol/L (n = 51); and group 3, TGs >9.04 mmol/L (n = 9). Results: In group 2, a RLP-C-to-total TG molar ratio ≥0.23 (≥0.10 when using mg/dL) and a VLDL-C-to-total TG molar ratio ≥0.69 (≥0.30 when using mg/dL) correctly classified 94% and 90% of the subjects, respectively. The utility of the RLP-C-to-total TG ratio in diagnosing type III HLP decreased in patients in the other two groups. Conclusion: When used in an appropriate target population, the RLP-C-to-total TG ratio is a convenient and effective alternative to ultracentrifugal and electrophoretic methods for diagnosing type III HLP.