Is unconjugated bilirubin normally present in urine?

Is unconjugated bilirubin normally present in urine?

• A. Yes
• B. No
• C. Only in certain diseases
• D. Only in infants

Answer: (B)

Unconjugated bilirubin is not normally present in urine because it is not water-soluble. The liver processes bilirubin through conjugation with glucuronic acid, transforming it into conjugated bilirubin, which is soluble in water. This water-soluble form is excreted in bile and can enter the urine.

In a healthy individual with normal liver function, unconjugated bilirubin remains in the bloodstream and is eventually metabolized by the liver, thereby preventing its presence in urine. The detection of bilirubin in urine generally indicates an increased level of conjugated bilirubin, often due to liver conditions or disorders that cause the liver to leak conjugated bilirubin into the bloodstream and, subsequently, to the urine.