In this lecture, I’m going to discuss
hyperbilirubinemia in the newborn.
Here is a child with hyperbilirubinemia.
This is almost always a
completely benign condition.
But it can be either
physiologic or pathologic.
And it is important for you to be
able to distinguish the difference.
Remember, almost half of infants
will have visible jaundice
after birth as a result
So in newborns, basically,
they have a higher hemoglobin
and at that period in their
life then never again.
This results with an increased
release of hemoglobin
because of red blood
Remember, newborn red blood cells have
a shorter half life, about 70 days,
compared to adult red blood
cells around 120 days.
And during the newborn period, there
is less efficient hepatic conjunction
of the bilirubin and excretion
into the intestinal tract.
So let’s go through the physiology of it.
There’s breakdown of hemoglobin
and other heme proteins.
This results in an
which is about half the
time bound to albumin.
If there is free bilirubin
in high levels,
this cross into the blood brain
barrier and cause kernicterus.
And kernicterus is brain damage.
We want to avoid that.
So we have this whole system of getting the
unconjugated bilirubin out of the blood.
It gets conjugated in the liver
and then the conjugated bilirubin is
extruded through the biliary tract
and into the stool, which is
secreted as stercobilinogen,
which is what makes our stools brown.
However, some of it does go
through enterohepatic circulation
and get reabsorbed and go
back up and do it again.
Additionally, a small percentage
will go to the kidneys
and be peed out as urobilinogen.
So hyperbilirubinemia in an infant
may not just be a problem with increased
red blood cells breaking down
or a problem with the
conjugation or extrusion
of the bilirubin through
the normal systems.
It could be a sign of another problem.
And so we worry a little
bit about these babies
and we think could there be
something else going on.
An example is hemolytic anemia.
So an infant who’s having an
autoimmune hemolytic anemia
and that’s common and we’re going
to talk about it in a little bit.
Those infants are going to have
more red blood cell breakdown
than a regular baby would.
And they will generally turn yellow.
Infants who are infected for whatever
reason can present with jaundice.
Infants with metabolic disease
can also present with jaundice
and make sense that infants with liver
disease may present with jaundice as well.
So we see a baby, we think any of
these things could be going on.
Let’s talk a little bit first about what
happens if we don’t fix the problem.
In infants with very high levels of
this can result in Kernicterus and
you can see a brain here of a baby
who’s had deposition of bilirubin
in his brain parenchyma
where those two green
arrows are pointing.
This is bad for these children.
It can result in brain damage or death.
And in particular, affects
the basal ganglia,
which are responsible for coordination
of movement among other things.
Okay. What if it’s hyperbili
but it’s conjugated hyperbili
rather than unconjugated?
This is much rarer, but we
have to know the difference
because patients with conjugated hyperbili
do not respond to light therapy
the way our
unconjugated babies do.
So we need to know what it is
so we know how to treat it.
There are many different causes and
they’re generally intrahepatic problems.
An example would be bile duct
obstruction or a choledochal cyst,
which is preventing
drainage of that bile.
Alagille syndrome is whole syndrome
among which they have problems
with bile and bile duct extrusion.
They may have galactosemia, which can
absolutely cause a conjugated hyperbili.
They may develop alpha-1 antitrypsin
deficiency which can cause the liver damage
from the build up of that alpha-1
antitrypsin in the liver
and therefore, they can get problems
with conjugation of their bilirubin.
They may have a protein metabolism defect,
cystic fibrosis, or even
So there are many reasons,
even that I didn’t list,
that can cause a conjugated
hyperbili in infants.