Uniform Presentation of Enzyme Determinations

To the Editor.—  The letter of David E. Langdon, MD (241:1229, 1979), "SI Units and Enzyme Levels," remains pertinent to a continuing problem. The thrust of the author's remarks should be reiterated periodically, until the dissemination of the new confusion inherent in the International System of Units (SI) is curtailed. Our colleagues remain puzzled about the switch from mg% to mg/dL and other changes in scientific medical unit designations. Should we further the fiasco under the guise of accuracy when what follows is misunderstanding?The original expression for uniform presentation of enzyme measurements along the lines recommended by Dr Langdon was made by Harry L. Gerstbrein, MD, and William H. Lederer, PhD (227:325, 1974), to the best of my knowledge, although others may have preceded them. Gerstbrein and Lederer corrected all enzyme chemistry values so that the upper limit of normal is 100 (95th percentile for healthy adults). They designated