To      : Ellen Taylor
Re      : Maternal Bilirubin

I would like to add to the discussion of maternal hyperbilirubinemia, bilirubin
transfer into milk, and absorption by the infant.

First bilirubin will to some degree be secreted into milk, although I have
never seen a publication stating the amount.  Although it is rather high in
molecular weight(584) in the deconjugated form, it is highly lipophilic and I
still believe it would be present to some degree.   The statement that its
molecular weight would preclude its transfer to milk is only partially correct.
All kinds of high molecular weight drugs (such as Rocephin = 554) can penetrate
quite effectively if they have other physicochemical parameters that aid their
transfer through lipid membranes.  However, I believe the amount of bilirubin
transferred would probably be minimal.  But if the infant were
hyperbilirubinemic as well, then ...

As for the bioavailability of bilirubin,  you must remember that bilirubin is
easily reabsorbed from the GI tract of an infant during the early neonatal
period,  it's called enterohepatic reabsorption,  but ONLY in its unconjugated
form.  Breast milk enhances the bioavailability of bilirubin by assisting in
its deconjugation,  followed by its reabsorption as unconjugated bilirubin.

Larry Gartner has published eloquently and extensively on this subject and I
urge you all to read his papers.

Regards

Tom Hale