THE ICTERUS INDEX

Abstract

The two quantitative clinical methods now available for estimating the degree of bilirubinemia are (1) the van den Bergh and (2) the icterus index. The latter, although simple, has the disadvantage in that the degree of jaundice is expressed in arbitrary units of icterus index, instead of in milligrams of bilirubin, one unit being the color equivalent of a 1: 10,000 aqueous solution of potassium dichromate. It has been our aim in this work to inquire into the basic colorimetric relationships between potassium dichromate and various solutions of bilirubin and to assign, if possible, a definite value in milligrams of bilirubin to the dichromate dilutions. We have also investigated the effect of small amounts of hemolysis. Murphy¹ and Davis² have adequately reviewed the history of the icterus index. It has long been assumed that bilirubin was the pigment responsible for jaundice, as spectrophotometric analyses of jaundice serums correspond with the