Presence of unsedimented precipitate in visually non-turbid supernates in the heparin-manganese method for HDL-cholesterol quantitation.
An inherent problem with the heparin-manganese precipitation procedure for high density lipoprotein-cholesterol (HDL-C) quantitation is the inability to sediment all the precipitated lipoproteins, especially in hypertriglyceridemic samples. This results in overestimation of HDL-C. Thus ultrafiltration has been recommended for turbid supernates. We have investigated 47 non-turbid supernates for possible presence of unsedimented precipitate. Optical turbidity in these samples was found to correlate with the serum triglyceride level. With ultrafiltration of the supernates, there was a significant decrease in cholesterol, optical turbidity and apoprotein A-I. The percent change in turbidity correlated with the percent change in cholesterol. There was also correlation between percent change in cholesterol and the prefiltration supernate turbidity. These results indicate that visually clear supernates may show optical turbidity; the turbidity is likely due to triglyceride-rich particles, which contain cholesterol; the fall in cholesterol with ultrafiltration is due to removal of these floating particles and some adsorbance of HDL particles to the filters.
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000097:blood; D011232:Chemical Precipitation; D008076:Cholesterol, HDL / Q000032:analysis*; D006493:Heparin; D006801:Humans; D008345:Manganese; D014280:Triglycerides / Q000097:blood; D014462:Ultrafiltration / Q000379:methods*
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D008076:Cholesterol, HDL; D014280:Triglycerides; D008345:Manganese; D006493:Heparin