Calculation of LDL apoB

•Presently only total apoB can be measured routinely.•LDL apoB can be calculated from TC, TG, HDL-C, and apoB as long as TG < 3.00 mmol/L.•This will allow the atherogenic risk of VLDL apoB to be more clearly determined.

ObjectivesThis study tests the validity of the Hattori formula to calculate LDL apoB based on plasma lipids and total apoB.MethodsIn 2178 patients in a tertiary care lipid clinic, LDL apoB calculated as suggested by Hattori et al. was compared to directly measured LDL apoB isolated by ultracentrifugation.ResultsIn subjects with plasma triglycerides ≥ 3.0 mmol/L, there was considerable discordance between calculated and measured LDL apoB. In all others, the relation between measured LDL apoB and calculated LDL apoB could be expressed as LDL apoB = 0.86 [total apoB − 0.9 TC (mg/dL) + 0.09 HDL-C (mg/dL) − 0.08 TG (mg/dL)] − 7.0 (r > 0.91; P < 0.0001).ConclusionsOur results indicate that LDL apoB can be calculated with reasonable accuracy when triglycerides are <3.0 mmol/L. However, the calculation suggested by Hattori et al. should be corrected based on the regression demonstrated between calculated and measured LDL apoB in subjects with a plasma triglyceride <3.0 mmol/L.