Development and evaluation of a method for quantitation of plasma high-density-lipoprotein cholesterol.

An improved method for separating hii-density lipoprotein with use of “Alphachol” tubes containing pre-dispensed and lyophilized heparin and MnCl2 is described. Results for high-density lipoproteincholesterol(C-HDL) isolated by ultracentrifugation from a 360 mg/liter and a 510 mg/liter pool were compared with those for the same pools by the Alphachol (358 and 506 mg/liter) and standard Lipid Research Clinic (LRC) (354 and 504 mg/liter) procedures. The within-day coefficient of variation (CV) for the Alphachol method was 1%, as compared to 1.3% for the standard LRC method. The CV for between-day precision studiesconducted over 20 days was 5.3% forthe Alphachol,4.2% forthe standardLRC procedures.Analysisof C-HDL in 100 patients by both the Alphachol and the standard LRC method showed mean C-HDL valuesto be slightly (23 mg/liter) higher by the standard LRC method (P < 0.00 1). A similar mean difference (24 mg/liter, P < 0.001) was obtained on comparing 75 patients sera analyzedby the Alphacol and modified LRC (final MnCl2 concentration, 92 mmol/liter) methods. It is unlikely that the 20 mg/liter difference between methods would have clinical significance. There was good correlation between C-HDL measured by Alphachol and both standard and modified LAG methods; r = 0.98 and 0.96, respectively. The Aiphachol system obviates the need for careful, accurate heparin-MnCI2 preparation and delivery, and a correction factor to account for dilution of plasma by liquid reagents, and allows a much higher rate of analysis.