2015 Volume 64 Issue 5 Pages 534-540
Because the strips used for the urine bilirubin test by the diazo coupling method often show a false positive result, confirmatory examinations of bilirubin true positivity are necessary. To determine urine bilirubin, there are the Rosin method, the Harrison method, and the Watson-Howkinson method, which are based on oxidation reaction. We evaluated these methods, including the procedures of the Harrison and Watson-Howkinson methods, to determine the most suitable confirmation method. As a result, we chose the Watson-Howkinson method (W method-C). In the W method-C, the preservation of the absorption pad was easy, and the procedure was simple, easy, and required a short time and a small sample volume. Then, we examined the W method-C in terms of the absorption pad to be used, the smallest sample volume, the detection limit, and the coincidence rate with Ictotest. We concluded that One-Shot Dry was the most suitable absorption pad, because the color that developed was easy to judge with only three drops of urine. The rate of agreement with Ictotest was good at 92.6%. The W method-C is also cheap, and thus it can sufficiently be used as a confirmation test of urine bilirubin on a routine basis.