Indirect-reacting bilirubin may be quantified initially in which reagent?

Indirect-reacting bilirubin may be quantified initially in which reagent?

• A. Dilute hydrochloric acid
• B. Dilute sulfuric acid
• C. Caffeine-sodium benzoate
• D. Sodium hydroxide

Answer: (C)

Indirect (unconjugated) bilirubin is not water-soluble, so it must be solubilized before it can participate in the diazo reaction used to measure bilirubin. Caffeine-sodium benzoate acts as a solubilizing medium, forming a soluble complex with the unconjugated bilirubin and allowing the subsequent diazo reaction to proceed. This makes it the best initial reagent for quantifying indirect bilirubin. The acidic or basic reagents listed aren’t used to solubilize unconjugated bilirubin; they serve other roles in the reaction environment but don’t enable the initial solubilization needed for the measurement.

Indirect (unconjugated) bilirubin is not water-soluble, so it must be solubilized before it can participate in the diazo reaction used to measure bilirubin. Caffeine-sodium benzoate acts as a solubilizing medium, forming a soluble complex with the unconjugated bilirubin and allowing the subsequent diazo reaction to proceed. This makes it the best initial reagent for quantifying indirect bilirubin. The acidic or basic reagents listed aren’t used to solubilize unconjugated bilirubin; they serve other roles in the reaction environment but don’t enable the initial solubilization needed for the measurement.