From the Guidelines
Increased urobilinogen in urine or stool is a significant indicator of potential liver dysfunction or hemolytic disorders, and its interpretation should be approached with a thorough diagnostic workup to determine the underlying cause. When interpreting elevated urobilinogen, it is crucial to first determine if the increase is in urine or stool, as this affects the diagnostic approach. In urine, normal values range from 0.1-1.0 Ehrlich units, with higher levels suggesting liver disease (hepatitis, cirrhosis), hemolytic anemia, or severe infections 1. For accurate interpretation, correlate the finding with other liver function tests like bilirubin, ALT, and AST. Some key points to consider in the interpretation and further evaluation include:
- Correlating urobilinogen levels with clinical symptoms and other laboratory findings to assess for liver disease or hemolysis.
- Considering additional testing such as a complete blood count to assess for hemolysis and imaging studies like ultrasound or CT scan of the liver if hepatic pathology is suspected.
- Recognizing that increased urobilinogen occurs because urobilinogen is formed when bilirubin is reduced by intestinal bacteria; when excess bilirubin enters the intestine (as in hemolysis) or when the liver cannot effectively recirculate urobilinogen (as in liver disease), levels rise.
- If hemolysis is confirmed, further workup for causes like autoimmune hemolytic anemia, sickle cell disease, or G6PD deficiency may be necessary, as suggested by guidelines for evaluating abnormal serum liver chemistries 1. Given the potential for significant morbidity and mortality associated with untreated liver disease or hemolytic disorders, a thorough and expeditious evaluation is essential in patients with significant symptoms or evidence of chronic or decompensated liver disease.
From the Research
Interpreting Increased Urobilinogen
Increased urobilinogen can be an indicator of various health issues, including liver disease and hemolytic anemia.
- Urobilinogen is a byproduct of bilirubin breakdown, and its levels can be measured in urine, feces, bile, and serum 2.
- Elevated urobilinogen levels may suggest increased bilirubin production, which can occur in cases of hemolysis or liver dysfunction 3, 4.
- A study found that urine urobilinogen assays can be used as a screening test for liver function test abnormalities, with a sensitivity of 70-74% and specificity of 77-87% 5.
- In cases of hemolytic anemia, increased urobilinogen levels can be accompanied by other laboratory findings such as anemia, reticulocytosis, and elevated unconjugated bilirubin 4.
- The diagnosis of hemolysis is based on the presence of anemia with sustained reticulocytosis, and additional findings can include marrow erythroid hyperplasia and decreased haptoglobin and hemopexin 4.
Clinical Utility of Urobilinogen Assays
- Urine urobilinogen assays can be used to screen for liver function test abnormalities, with a positive predictive value of 83-86% 5.
- A normal/abnormal threshold of 2.0/4.0 mg/dL can be used to determine the clinical utility of urine urobilinogen as a screen 5.
- The measurement of urobilinogen levels can be performed using direct spectrophotometry or spectrofluorometry of a zinc complex, with high sensitivity and specificity 2.