Problems with PEG-based precipitation methods in the determination of HDL2- and HDL3-cholesterol

In this study a comparison of two polyethylene glycol (PEG)-based precipitation methods, that is, one using PEG-6000/DS-15000 and the other using two different concentrations of PEG-20000 are presented. The total HDL-cholesterol values measured with the PEG-6000 procedure were higher (13%) than those measured with PEG-20000 (r = 0.91) in 16 pooled serum samples tested. The HDL2- and HDL3-cholesterol values measured with the two methods differed markedly from each other in spite of the moderate correlation (HDL2: r = 0.74; HDL3: r = 0.26) observed. The advantage of the PEG-20000 method as compared with the other method was its simplicity and rapidity. The separation of HDL2/HDL3 is more or less arbitrary in both methods used and further studies are needed for the estimation of optimal conditions for subclass separation.