Weiss Reaction

WEISS REACTION (Moritz Weiss), or urochromogenic reaction, is performed as follows: to filtered and three-times diluted urine in a test tube, three drops of a 0.1% solution of potassium hypermanganate are added; definite yellowing of this test tube, compared with a control, indicates a positive reaction; this depends on the transition of colorless urochromogen into the ordinary yellow pigment of urine (urochrome). The presence of significant amounts of urobilin and bilirubin interferes with the reaction, and they must be removed by salting out with ammonium sulfate (to 20 cubic cm of urine, 16 g of ammonium are added, mixed, and after standing for 1/4 hour, filtered; the W.r. is performed with the filtrate). Urochromogen appears in urine with increased tissue breakdown and insufficient oxidation of the products of this breakdown. Very often such urine also gives a positive Ehrlich diazo reaction; but the question of the identity of the substances causing both reactions, expressed by Weiss, cannot be considered resolved. The reaction appears in typhoid and typhus, measles, chronic purulent processes, and tuberculosis, where it has found particular application, since it turned out that the reaction can often indicate a poor outcome before clinical data.