Abstract
Cholesterol in lipoprotein has been estimated by analyzing the ultracentrifuged (UC) or precipitated material of serum, and also by calculation following Friedewald's formula. Preparative ultracentrifugation, being a time-consuming procedure, is not always available for routine laboratory work. Some inaccuracies have been stated in calculation following Friedewald's formula in cases with hypertriglyceridemia.
Recently Assmann et al developed a new LDL-cholesterol (LDL-Ch) assay method precipitating LDL by polyvinyl sulfate (PVS).
This paper describes an investigation of LDL-Ch by PVS method and compares with other methods.
Serum specimens were collected from 62 adults comprised of 24 with the triglyceride (TG) level of 150mg/dl or below, 15 with 180 to 299mg/dl and 23 with 300 to 520mg/dl. Chylomicron was removed after an overnight refrigeration at 4°C. Polyacrylamide gel disc electrophoresis for the supernatant separated by addition of PVS to serum demonstrated no LDL band indicating the complete sedimentation of LDL.
LDL-Ch level was higher in PVS method than in UC. The intraassay coefficient of variation of LDL-Ch by PVS method was 1.3% (n=10). The values obtained by PVS method and calculation following Friedewald well correlated positively with that obtained by UC irrespective of TG level. The inaccuracy of calculation following Friedewald owing to TG might be eliminated by the removal of chylomicron containing much TG in our observation.
PVS and Friedewald methods are superior to the ultracentrifugation method in clinical observation of dyslipoproteinemia, both methods should be widely applied in clinical practice.
