Accuracy of urine urobilinogen and bilirubin assays in predicting liver function test abnormalities.

Components of the dipstick urinalysis (urine urobilinogen and urine bilirubin) are often used by emergency physicians to screen for the need to obtain liver function tests in many clinical situations. A prospective observational study was conducted to evaluate the sensitivity, specificity, and predictive properties of spot urine bilirubin and urobilinogen assays in the emergency department as screening test for serum liver function test (LFT) abnormalities. Of 122 patients, abdominal pain was the indication for laboratory evaluation in 54%; jaundice and constitutional symptoms were the indication in 29%. Overall sensitivities for both urine assays were 70% to 74% for serum bilirubin, but 43% to 53% for other LFTs; specificities were 77% to 87% for both urine screens. Positive predictive values show that the urine assays were 83% to 86% reliable for detecting at least one LFT abnormality. Negative predictive values were 85% for both urine assays for serum bilirubin elevations, but lower for other LFTs. Urine urobilinogen has its greatest clinical utility as a screen when a normal/abnormal threshold of 2.0/4.0 mg/dL is used.