“This finding underscores the importance of improving, standardizing, and validating techniques to measure unbound circulating bilirubin”
New England Journal of Medicine, November 21, 2013
A Fluorescent Assay for Unbound Bilirubin
"Although recent studies suggest the usefulness of free bilirubin measurements...there currently exists no widely available method to assay the serum free bilirubin concentrate"
Amin, Semin Perinatol 2011 Jun; 35(3): 134-140