Newborn Jaundice

de: Struktur von Bilirubin en: Structure of bilirubin (Photo credit: Wikipedia)

Newborn Jaundice:

Not Really Jaundice

Not Really Harmful

Nearly every newborn develops some sort of yellowish tinge to the whites of their eyes or their skin sometime in the first week of life.  This tinge is commonly referred to as newborn jaundice, a phrase that suggests something is quite wrong.

But the facts are that this yellowish hue reflects normal functioning of healthy bodies.   The chance that the accumulation of the yellow material that causes the color change causing any harm, you will see, is remarkably remote.

The story of the yellow hue in the first week of life revolves around a most interesting pigment, called bilirubin.  Bilirubin turns out to be the waste product after the body is done getting rid of old stores of another brightly colored pigment, the red chemical hemoglobin.  Now, in nearly every animal, hemoglobin is gotten rid of by a conversion to biliverdin.  Biliverdin is a beautiful soft-blue pigment (its the pigment in robin's eggs), and it is cleared from the body simply via urination, it never accumulates.  But in humans and only one other animal, the biliverdin is processed one more step to the yellow pigment bilirubin.

Bilirubin does not dissolve in water, at all, which means it must be further processed to be converted to a form that does, and that step requires your liver to take that action.

During pregnancy, the bilirubin made by the fetus is cleared from both fetus and mother by the mother's liver.

After birth, the newborn's liver takes 1-2 weeks to start clearing the bilirubin.  This is exactly why all babies born see a rise in their bilirubin level.  It's during that 1-2 weeks that they wait for their liver to process their own bilirubin that it rises, often to a point where the whites of the eyes and/or skin takes on the yellow hue of the bilirubin.

Most items written about this yellow glow seem to suggest this is a sign of liver dysfunction, that the 1-2 weeks of waiting for the liver to start clearing the bilirubin is a defect, a lapse.  It is not clear this is the case.

It costs the body a lot to make bilirubin out of biliverdin, remember that not many animals do that.  And once it is made, it costs a lot of energy to clear the bilirubin.  So one could make the case that the body goes to a lot of effort to create bilirubin when it could simply clear old hemoglobin by letting it stay converted to biliverdin.  

Dr. Anthony McDonough of the University of California in San Francisco offers an intriguing insight.  Tony just won an award from the American Academy of Pediatrics as one of our nation's top research scientists.  He has devoted his life to the study of these brightly colored molecules: hemoglobin, biliverdin, bilirubin, chlorophyll, all of which are closely related to each other.   He taught me many years ago, and still teaches, that bilirubin is a very strong anti-oxidant.  Not too long ago, proof of this concept was supported by an article demonstrating that the higher the normal bilirubin levels are, the more protected the group is from events like heart disease and cancer.

The point is that the body might actually be going to great lengths to offer the newborn a boost of bilirubin, the yellow glow may actually reflect something good happening.

Given all this, why is so much fuss made over this nearly universal occurrence?  The reason is that in very special and unfortunate circumstances, bilirubin has been found to be irritating to the brain.  Those circumstances are severe prematurity combined with very severe illness, such as a serious infection.  In settings where the body is under rather extreme distress, bilirubin in the blood is able to enter the tissue of the brain and cause harm.   When a newborn is healthy and full-term, a very sturdy barrier keeps bilirubin out of the brain.

So then why any concern about bilirubin in full-term, healthy newborns?   Not too long ago, some reports documented an instance or so of bilirubin, when in excess levels, getting into the brain of even a healthy, full-term infant.  The chance of that happening is nearly astronomically remote.  About 4 million babies are born in the US every year, and the number of healthy newborns where bilirubin causes harm is less than one every year.   To my mind, when a substance causes harm less than 1 in a million exposures, that says to me its pretty safe.  Consider penicillin which causes serious harm in 10 of every million doses, and we consider that risk of harm so remote it is deemed to be very, very safe.

Another sign that the mild rise seen in nearly every baby in bilirubin after birth is normal and perhaps beneficial is that the rise is higher in babies who are breast-fed than formula-fed.  For many years this was viewed as one of the only disadvantages to nursing, but it may be a further hint that the body is really trying to bump the bilirubin level up a bit for the few weeks after birth.

BOTTOM LINE:

Nearly every baby born experiences a transient, 1-2 week rise in their level of the yellow molecule, bilirubin.

Very many have sufficient increase to look a bit yellow.  In healthy, full-term infants this experience is overwhelmingly harmless, and may even be designed and helpful.

When to worry?  If the yellow glow becomes a deeper, more severe, orange hue.  Bilirubin levels should not rise so high to cause your newborn's color to get too intensely orange.  If that happens let us know.

But the mild yellow hue, the glow seen so often, is not harmful, and may turn out to be just what the baby needs.

Dr. Arthur Lavin

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