The total apolipoprotein B/LDL-cholesterol ratio does not predict LDL particle size

Small dense low density lipoprotein (LDL Pattern B) particles are associated with low plasma concentrations of high density lipoprotein (HDL)-cholesterol and high concentrations of triglyceride and also with occurrence of coronary heart disease. Because LDL size is not measured easily, the ability of plasma total apolipoprotein (apo) B and a calculated LDL-apo B combined as a ratio with LDL-cholesterol (Friedewald) to predict LDL Pattern B (peak LDL size < 25.5 nm) was examined in 100 plasma samples with triglyceride 0-5 mmol/l. LDL-apo B was calculated using the regression line comparing measured LDL-apo B total apo B with triglyceride and was correlated strongly (r = 0.94) with measured LDL-apo B. There was no difference in either ratio between plasma samples with LDL Pattern A (peak LDL size ≥ 25.5 nm) or Pattern B for samples with triglyceride > 2.0 mmol/l. An apo B cholesterol ratio was measured for LDL separated by ultracentrifugation and was higher in plasma with LDL Pattern B than Pattern A (P = 0.018). Nevertheless, in combination with LDL-cholesterol, neither total apo B nor a calculated LDL-apo B was useful in predicting LDL particle size.