Urine Urobilinogen

Urobilinogen is produced within the intestinal lumen by bacterial action on the bilirubin present in the bile coming into the gut from the biliary system. It is partially absorbed into the portal vascular system and returned to the liver through this enterohepatic route to be processed by hepatocytes and  excreted into the bile and reabsorbed by the intestine back into the blood. Therefore, there is ongoing intestinal absorption of newly created and old excreted urobilinogen. At usual levels of hematological stability and  hepatobiliary activity, a small fraction spills into the urine from the kidneys. If the system is overloaded (as with surges of hemoglobin coming to the liver), excess urobilinogen spills into the urine. If there is insufficient hepatocytic mass or processing sufficiency, excess urobilinogen spills into the urine. If the extrahepatic biliary system is obstructed, one may fail to detect urobilinogen in the urine (or stool). The test performs best on fresh urine.

• Urine positivity elevated:
  • Hepatitis
  • Cirrhosis
  • Liver Metastases
  • Liver infarction
  • hemolytic jaundice
  • resolution of large hematomata or hemorrhagic infarcts
  • CHF
  • dipstick test can be false pos. due to high pH or meds
• Urine negative
  • total obstruction of bile excretion, either due to duct obstruction or hepatitic swelling

References:

1. Wallach, 7th Ed, Interp. of Diagnostic Tests. (EBS's office)
2. McKenna and Keffer, The Handbook of Clin. Path., 2nd Ed. (EBS's office)