Internally reviewed The following descriptions are written as generic and inclusive of the major products used on the market today. For specific information always consult the package insert that comes with the product that you are using. The pseudoperoxidase action of erythrocytes and hemoglobin catalyzes the oxidation of various chromogens to produce the color change. The color is produced through a double enzymatic reaction of glucose oxidase and peroxidase. The latter enzyme reacts with a chromogen to produce the final color.
Ketones react with nitroprusside or sodium nitroferricyanide and glycine to produce a color change.
Leukocyte esterase, present in granulocytes, catalyzes the reaction of the chromogens to produce a color change. These nitrites then react to form a diazonium salt which in turn reacts with a chromogen to produce the final color. The urine from one reagent area carries reagent onto the pH test area and changes the result erroneously. Urobilinogen reacts with a chromogen to form an azo dye which appears as various shades of pink or purple. This reaction occurs best at room temperature.