Analytic aspects and clinical interpretation of serum bilirubins

The clinical importance of serum bile pigments is reflected in the large number of bilirubin measurements performed worldwide in clinical laboratories. Nonetheless, conventional methods currently in use have major limitations, in particular with respect to differentiation of the various bilirubin fractions. Hence, efforts continue to improve the analytical methodology, as is evident from the steady stream of reports describing modification aimed at improving the specificity of serum bilirubin differentiation. Confusion still exists with regard to the interpretation of results of serum bilirubin analyses. These considerations illustrate the need for a better understanding of the physiology, pathophysiology, and basic chemistry of the bile pigments found in serum. Clinically important aspects of these issues are addressed in the present article. This should enable clinicians to reach a better insight into the limitations and significance of measuring serum bilirubin levels in different clinical settings.