PURPOSE: To improve the accuracy and sensitivity of an assay by using a specific indicator reagent composition and effectively stabilizing an indicator dye present in the indicator reagent composition prior to the contact between the indicator reagent composition and a test sample.

CONSTITUTION: A qualitative or quantitative test on active peroxides such as a hemoglobin and a myoglobin in urine or another test sample by using a bicyclic boric acid amide containing an indicator dye, hydroperoxide, methyl group or ethyl group as a side chain and a stable indicator reagent composition containing a buffer agent. The bicyclic boric acid amide is structured as shown in Formula. further, R1, R2 and R3 represents independently a methyl group or an ethyl group, and m, n and p are a number in a range from 1 to approximately 3. These indicator reagent compositions stabilize an indicator dye and reject the early oxidation of the indicator dye by a hydroperoxide before the contact between an indicator reagent composition and a test sample.