Free (unconjugated) bilirubin

Free Bilirubin Test - Liver Function Assessment

The test measures the concentration of unesterified bilirubin - free bilirubin, which circulates in the blood bound to albumin. In this form, bilirubin is transported to the liver, where it can be converted into conjugated bilirubin.

When to Perform the Test?

The test is performed to assess liver function and for the diagnosis and differentiation of jaundice.

Disease Entities

Elevated levels of free bilirubin are associated with hemolytic jaundice (massive hemolysis of erythrocytes), hepatic jaundice (Gilbert's syndrome, impaired bilirubin uptake into hepatocytes), disorders of conjugation with glucuronic acid in enzyme deficiencies (glucuronyl transferase deficiency, Crigler-Najjar syndrome), and liver damage.

Symptoms

Free (unconjugated, indirect) bilirubin measurement is performed when symptoms such as jaundice (yellowish discoloration of the skin and mucous membranes), especially in newborns, right upper quadrant pain, ascites, and changes in urine and stool color are observed.