Lactate dehydrogenase isoenzyme 1 activity in sera of patients with ovarian cancer.

both 2ME-treated and untreated samples. To allow us to compare the methods directly, we selected sera containing 1gM paraproteins, for which quantification in treated and untreated samples by E-SD was possible. Figure 1 shows the regression analysisbetween treated and untreated samples with 1gM paraproteins. The median concentration for untreated 1gM (mainly 19S) was 26.9 g/L (range 5.8.46.8 g/L) and for treated 1gM (7S) median value was 27.3 g/L (range 5.942.9 g/L), with no significant difference detectable between the two measurements by Wilcoxon Rank test. We conclude that, in cases where reduction of a 19S 1gM paraprotein to 7S 1gM would aid its resolution by electrophoresis, the densitometric analysis of the reduced 7S monomeric paraprotein is not significantly different from that of the 19S pentamer. We therefore recommend electrophoresis followed by scanning densitometry for the quantification of 1gM paraproteins in either 2ME-treated or untreated samples.