Most newborns will have some jaundice.  Most jaundice is benign. So, how can we sort through the various presentations and keep our newborns safe? Pathologic Jaundice When a baby is born with jaundice, it’s always bad.  This is pathologic jaundice, and it’s almost always caught before the baby goes home.  Think about ABO-incompatbility, G6PD deficiency, Crigler-Najjar, metabolic disturbances, and infections to name a few.  Newborns are typically screened and managed. Physiologic Jaundice Physiologic jaundice, on the other hand, is usually fine, until it’s not. All babies have some inclination to develop jaundice.  Their livers are immature.  They may get a little dehydrated, especially if mother’s milk is late to come in.  In today’s practice, we are challenged to catch those at risk for developing complications from rising bilirubin levels. Hyperbilirubinemia is the result of at least one of three processes: you make too much, you don’t process it enough, or you don’t get rid of it fast enough. Increased production Bilirubin mostly comes from the recycling of red blood cells. Heme is broken down in in the liver and spleen to biliverdin then bilirubin. Normal, full term babies without jaundice run a little high -- bilirubin production is two to three times higher than in adults, because they are born with a higher hematocrit.  Also, fetal hemoglobin is great at holding on to oxygen, but has a shorter life span, and high turn-over rate, producing more bilirubin. Impaired conjugation Think of bilirubin as your email.  Unconjugated bilirubin is your unread email.  To process it or get rid of it – you have to open it.  Of course, the more unread messages that accumulate, the more unwell you feel. Conjugated bilirubin is your opened and processed email.  So much easier to sort out, deal with, and get rid of. Decreased excretion Both unread email and unconjugated bilirubin continue to float around in your inbox.  Unconjugated bilirubin keeps getting reabsorbed in the intestinal mucosa through enterohepatic circulation. Processed email and conjugated bilirubin are easier to sort out.  Conjugated bilirubin is water soluble, so it goes right into the read folder in your gallbladder, and is excreted off your inbox.  Later on down the line in the intestine, conjugated bilirubin can’t be reabsorbed through the intestinal mucosa.  Like when you open an email and forget about it – it passes on through, out of your system. Newborns are terrible at answering emails.  There is a lot of unread unconjugated bilirubin is floating around.  The liver and spleen are just not able to keep up. Also, newborns have a double-whammy administrative load.  Normally, bacteria in the gut can further break down conjugated bilirubin to urobilin and get excreted in the urine.  The infant’s gut is relatively sterile, so no admin assistance there.  Just to add to the workload a poor little newborn has to do – he is being sabotaged by extra beta-glucuronidase which will take his hard-earned conjugated bilirubin and unconjugate it again, then recycle it, just like email you “mark as unread”. How Does this All Go Down? The recommended followup is 48 hours after discharge from the nursery for a routine bilirubin check, often in clinic, and often via the transcutaneous route. More Specifically: Infant Discharged Should Be Seen by Age Before age 24 h 72 h Between 24 and 48 h 96 h Between 48 and 72 h 120 h The neonate will end up in your ED off hours, if there is concern, if his status deteriorates, or simply by chance.  We need to know how to manage this presentation, because time is of the essence to avoid complications if hyperbilirubinemia is present. Critical Action #1: Assess risk for developing severe hyperbilirubinemia. This will tell you: check now in ED or defer to clinic (default is to check). Risk Factors for Developing Hyperbilirubinemia Total serum bilirubin/Transcutaneous bilirubin in high-risk zone Jaundice in first 24 hours ABO incom