Mostly in the past when I've taken care of people with jaundice it's because they have really bad liver disease. So bad that their livers can't get rid of bilirubin, a waste product of erythrocytes (red blood cells). In babies, it usually works a little different. Their livers are immature, but aren't usually damaged as much as they are overloaded with more bilirubin than they can handle.
But first I'll explain the normal physiology of bilirubin production and elimination: Like a lot of the waste products in your body, bilirubin is transformed multiple times, and different molecules are added or subtracted so the waste product is 1) less toxic 2) easier for your body to identify and get rid of, because they can recognize that it's trash.
Most bilirubin comes from heme: a component of erythrocytes (or Red Blood Cells), where it exists as hemoglobin.
"Hemoglobin" is the part of the red blood cell that makes it red: it has the iron that holds on to the oxygen in your blood, and it's the thing that makes your blood red when it touches air; blue when it is oxygen deprived. It's a very important component of your blood, however erythrocytes, only live a short amount of time (120 days in adults, 70 days in fetuses) and they don't reproduce.
When they die, the body needs a way to get rid of the parts it doesn't need anymore. A lot of the bodies waste products are excreted by the kidneys, but heme is usually excreted from the liver into your intestines as a component of bile.
I'm gonna show you a picture just to give you an idea of how heme is transformed on it's way to leave your body:
^ When red blood cells die, they release the "heme" from the "globin" and the heme exists in a form called bilirubin.
It would be just sitting around in the blood, but luckily there's a really big, powerful protein (called Albuimin) already circulating in the blood that binds the bilirubin to itself and carries it where it needs to go. In this form, (attached to the Albumin) the bilirubin is called "Unconjugated". The unconjugated bilirubin travels to the liver where it is processed and sugars are attached to the Albumin-Bilirubin molecule. In this form, we call it "Conjugated" bilirubin, because of the way all those smaller molecules (sugar, protien, bili) are bonded together.
This form it should not be circulating in the blood, it should be excreted into the intestines, get broken apart by all the bacteria living there, and go out with all of your poop. But sometimes, if it sits in your intestines for too long (this happens when babies don't feed well) or you don't have enough intestinal flora growing in your gut (newborn babies have very little), it can be re-absorbed into the blood.
Your body, of course, tries to find other places to put it (it is a waste product after all, it's TOXIC!) and, a very small amount (1 percent) is converted to urobilinogen and excreted from the kidneys, but it's really not very much. So the conjugated bilirubin just kinda gets stuck in your body
E.V.E.R.Y.W.H.E.R.E.
It can get so bad, you can see it in your skin. It was red in your blood, but now it's YELLOW:
and your eyes!
(This condition is called "Jaundice" or icterus)
But the WORST is when bilirubin gets to your brain, because it ends up causing encephalopathy and brain damage. (this is called Kernicterus)
Although Jaundice is relatively common in infants it's usually not a really big problem, most babies do have some degree of physiologic jaundice because their livers are immature. In a healthy infant who is feeding well usually won't need any treatment. Therefore, its important for parents to be able to distinguish when jaundice is progressing into a problem.
Jaundice can be particularly pathologic if it exhibits within the first 24 hours of an infants life. This is usually caused by an underlying condition that's contributed to the baby's red blood cells dying:
- Blood incompatability between the mother and the infant: Where the mother has produced coombs antibodies to the infant's blood.
- Infants with cephalohematoma, or bruising underneath their scalp (from a prolonged or traumatic birth)
- Infants who born earlier, who are small for gestational age, or twins, may have blood that's concentrated, and dies quicker
- Infection, or treatment with certain antibiotics.
- Respiratory distress/hypoxia
- Certain enzyme/metabolism disorders (Such as Gilbert's syndrome)
- Infants of asian parents (?? for some reason...their RBC's die quicker...idk...)
If a baby has these risk factors, it's important to monitor for symptoms of jaundice and inform the baby's doctor. There are screening tools like the transcutanous bilirubinometer (TcB) that you can use to determine if the baby is at risk for developing jaundice:
The doctor may order labs for the baby: Total Serum Bilirubin (TBIL, or TSB), Conjugated Bilirubin (Direct bilirubin, or DBIL) or Unconjugated Bilirubin (Indirect, or IBIL...which they basically get just by subtracting: TBIL-DBIL=IBIL)
The doctor might also place the infant's discharge on hold to monitor make sure jaundice isn't progressing and that he or she is eating enough to expel all of that bilirubin from their gut.
Aside from yellowing of the skin, and mucous membranes and eyes, babies with jaundice are usually poor feeders (either they aren't interested in eating, they have a poor suck, or they aren't pooping and peeing appropriately/enough for their day of life). They're usually really tired and won't startle as easily, they'll wanna sleep though feedings.
At the later stages, the baby's body will tense up, they'll be irritable, and they'll have a high-pitched or shrill cry.
Fortunately, there are a lot of things we can do to treat jaundice.
via a lighted blanket that sticks to their back,
a bili-bed,
or a bili-lamp...which kinda looks like a little tanning bed for babies, they even wear these little eye protectors:
If the baby's condition is critical, the doctor might order an exchange transfusion (I'd imagine this only gets done in the Neonatal Intensive Care Unit), where they take out blood, and put in new blood until the baby's circulating blood supply is completely replenished. Apparently this is particularly effective if there are a lot of antibodies in the babies system from mom, against the babies blood (if anyone knows more about this, I'd love to hear your experiences. It sounds like a pretty interesting treatment...I imagine they use whole blood, not Packed RBCs)
If a baby is going home with jaundice, or even if the baby is at risk, it's important that the baby's parents know that they're infant is at risk and know what signs and symptoms to look for that their infant might be developing this condition. Some yellowing is to be expected, but yellowing of skin and eyes accompanied by poor feeding is a concern. It's important that they know who to contact if the problem worsens (the pediatrician, NOT the obstetrician). It's also important that they keep well-baby follow up appointments with the pediatrician to make sure their baby is adjusting well to extra-uterine life.
Sometimes an infant with Jaundice will go home with a bili-blanket or bili-lights, sometimes the pediatrician will tell the parents to put the child in sunlight for a specific amount of time each day and to stimulate the baby to stay awake during feedings.
The risk for developing jaundice, and it's associated complications, is something we should assess in every baby. But it should not be something that causes a kid problems in the long run. Treatments for neonatal jaundice are very effective, as long as the symptoms are recognized and treated before it progresses to kernicterus. Doctors, nurses, and (most importantly) parents need to know what to look for in their infant, and when and how to seek help.
Sources:
http://www.vivo.colostate.edu/hbooks/pathphys/digestion/liver/neojaundice.html
http://medical-dictionary.thefreedictionary.com/bilirubin
https://labtestsonline.org/understanding/analytes/bilirubin/tab/test/
http://www.newkidscenter.com/How-to-Get-Rid-of-Jaundice-in-Newborns-at-Home.html
https://www.nlm.nih.gov/medlineplus/ency/article/007309.htm
http://www.lifewithkarma.com/2011/06/bili-baby.html
http://emedicine.medscape.com/article/1894477-overview
http://www.austincc.edu/emeyerth/hemoglob.htm
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