What reagent is utilized to measure urobilinogen?

Urobilinogen, a byproduct of bilirubin reduction, can be measured using Ehrlich's reagent. This reagent contains p-dimethylaminobenzaldehyde, which reacts specifically with urobilinogen to produce a colored complex. This reaction is crucial in clinical laboratories for assessing liver function and diagnosis of hemolytic diseases, as elevated levels of urobilinogen can indicate various pathological conditions.

The specificity of Ehrlich's reagent in forming a colored compound with urobilinogen is what makes it the standard for this measurement, distinguishing it from the other reagents mentioned. While Salkowski's reagent is commonly used in bilirubin tests, Gerhardt's reagent is associated with specific tests for phenols, and Folin's reagent is used primarily for total protein measurement in serum, none of these are suited for the measurement of urobilinogen. Thus, Ehrlich's reagent is the correct choice for this particular assay.