Which characteristic is true about conjugated bilirubin?

Conjugated bilirubin is indeed water soluble, which is a critical characteristic that distinguishes it from unconjugated bilirubin. When bilirubin is conjugated in the liver, it becomes bound to glucuronic acid, making it more soluble in water. This increased solubility allows conjugated bilirubin to be excreted efficiently in bile and, subsequently, in urine, which is an important aspect of bilirubin metabolism and clearance from the body.

Understanding this property highlights the clinical significance of measuring conjugated bilirubin levels, particularly in diagnosing and managing conditions like liver disease or biliary obstruction, where increased levels might indicate a dysfunction in the excretion pathway.

The other characteristics mentioned in the question do not accurately reflect the properties of conjugated bilirubin. It reacts more quickly than unconjugated bilirubin in certain assays, is less stable due to its solubility, and has different absorbance properties compared to unconjugated bilirubin, which has distinct spectral characteristics due to its structure.