A Fluorescence-Based Quantitative Analysis for Total Bilirubin in Blood and Urine

Abstract

Background: Bilirubin is a catabolic product of heme metabolism that circulates in the bloodstream in its unconjugated or glucuronide-conjugated form. Because the accumulation of bilirubin in the blood is a common symptom of liver diseases, its measurement in plasma (serum) is important for the diagnosis of these diseases. Method: We developed a method to assess total bilirubin levels in serum and urine, using the fluorescent protein UnaG and β-glucuronidase. Results: Our results indicate good correlation in serum total bilirubin levels between UnaG and the conventional bilirubin oxidase (BOD) methods. We found low levels of conjugated and unconjugated bilirubin in the urine of healthy subject individuals. Urinary bilirubin levels were elevated in patients with liver or bile duct diseases. A simple spot test of bilirubin using serum and urine showed a strong signal in patients with liver diseases. Conclusion: The proposed method to assess bilirubin levels in serum and urine will contribute to the accurate diagnosis of health conditions such as jaundice, anemia, and liver disease.