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From:
Sharon Knorr <[log in to unmask]>
Reply To:
Lactation Information and Discussion <[log in to unmask]>
Date:
Thu, 20 Dec 2001 18:24:27 -0500
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Hyperbilirubinemia is a very complex topic.  I got interested in it initially when my firstborn had to be admitted to the hospital with an elevated bili (19) which led to quite a week of trying to save breastfeeding while my baby was put on total formula feeds and light therapy.  Since then, I have done a lot of research on this and spoken on this topic several times at LLL confererences.  Being a med tech has made it a lot easier to understand the biochemistry underlying this condition.  But I am still learning.

You need to understand the complexity of bilirubin metabolism to get a handle on all of this.  Hemoglobin in the red cell is released when the cell is destroyed and part of it ends up as bilirubin in the bloodstream.  The bilirubin tries to bind with albumin and how successful that is depends on a lot of factors (the unbound bili is the stuff that can cause the brain damage known as kernicterus.) This bound bilirubin eventually travels to the liver where it separates from the albumin and undergoes several chemical processes, eventually being linked to a substance called glucaronic acid through a process commonly called conjugation.  This conjugated bilirubin is now water soluable and can be eliminated from the body by passing into the bile and then into the intestines.  In the intestines, bacteria transform the bilirubin into several other substances which eventually pass out in the stool (and give most stools their characteristic brown color.)

So what does this have to do with breastfeeding?  The meconium contains a lot of bilirubin which can be reabsorbed into the bloodstream.  So, moving the meconium out of the body as quickly as possible is one way to keep bilirubin levels from rising - babies who are not nursing well the first few days are at risk what is sometimes called "starvation induced hyperbilirubinemia."  Feeding formula will get the meconium moving.  So will feeding expressed or donated breastmilk.

Also, bacteria in the gut can produce an enzyme, beta glucaronidase, which can actually unconjugate or break the bonds between the bilirubin and the glucaronic acid - this free bilirubin can then be reabsorbed back into the bloodstream.  Thus the added concern if stools are not moving regularly through the system.  In addition, there seems to be a substance or substances in the breastmilk which also causes the deconjugation of bilirubin in the gut and/or hinders the initial conjugation of bilirubin in the liver.  Studies have not yet proven what this is - enzymes and fatty acids are implicated thus far.  Therefore, even in a breastfed baby that is eating well, it is likely that the bilirubin levels would fall faster if that same baby were receiving formula instead.  I'm not sure about formulas actually "clearing" the bilirubin, but there are other substances besides glucaronic acid (glucose being one) that can conjugate with bilirubin and that may be what Gartner and others are talking about.

I don't have the reference right at hand, but I believe that heating the breastmilk to 56 degrees C will destroy some of the jaundice-inducing properties and could be used in place of formula to bring down bilirubin levels more quickly.

The real question is at what point is a bilirubin so elevated that the risk of introducing formula is outweighed by the risk of kernicterus. I would think that in most cases, the introduction of formula is a severe overreaction to a relatively benign condition.  That being said, premies and sick babies can develop kernicterus at levels much lower than a healthy, term infant - so be sure that you get all the facts before you start making assumptions about the safely of a particular bilirubin level.

I hope this clears things up just a bit.  If anyone has any other info, please pass it along.  I am going to search for the references about formula actually binding with bilirubin.


Warmly,
Sharon Knorr, BSMT, ASCP, IBCLC
Newark, NY (near Rochester on Lake Ontario)
mailto:[log in to unmask]

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