Abstract
Calcium bilirubinate, a water-insoluble salt of bilirubin forming the major component of the pigmented calcium stone, was synthesized in vitro either by addition of calcium hydroxide into solutions of sodium bilirubinate or potassium bilirubinate, or by suspending free bilirubin immediately into a solution of calcium hydroxide. In this case, it was revealed that no structural change took place in the bilirubin moiety since free bilirubin, associated with the same absorption characteristics as the standard preparation, could be recovered from the synthesized calcium bilirubinate by treatments with hydrochloric acid followed by a chloroform extraction.
