Accuracy of lactate dehydrogenase isoenzyme estimations by a thin-layer agarose fluorescent technique: experience with ternary and quaternary mixtures of purified human lactate dehydrogenase isoenzymes.

We have further assessed the accuracy of the thin-layer agarose fluorescent technique of Elevitch et al. [Am J Clin Pathol 46, 692 (1966)]. Previously, we used semi-purified human lactate dehydrogenase isoenzyme-1 and -5 [Clin Chem 22, 1995 (1976)] and isoenzyme-1 and -2 [Clin Chem 27, 1708 (1981)] to show that this assay accurately measures the proportions of these binary mixtures. In the present study, using ternary and quaternary mixtures of isoenzyme- 1, -2, -3, and -5, we show that the assay gives accurate estimations of all of these isoenzymes, within the errors of the techniques used. We also show that peak area (integration) is more nearly accurate, but less precise, than peak height (amplitude) measurements.