<s>[INST] WHAT CAUSES JAUNDICE? [/INST] Jaundice occurs when there is a build-up of bilirubin in the blood.  

Bilirubin is a compound that all of us have in our bodies. It's a byproduct of the red blood cell life cycle, and fun fact, it's what makes our urine yellow and our poop brown.  As red blood cells get broken down at the end of their life cycle, some of their properties get turned into Unconjugated Bilirubin. (UCB).

For us to pass bilirubin out of our bodies, UCB must be transformed in our livers to create Conjugated Bilirubin (CB). CB then embarks on a journey from the liver to the gallbladder, eventually traveling to the intestines to be transported out in our waste (pee & poop). 

What causes Physiological Jaundice of the Newborn aka Newborn Jaundice is a combination of a large number of blood cells needing breaking down quickly and low levels of the liver enzyme that converts UCB to CB. Babies develop the yellowing as a direct result of the inability to clear the UCB from the bloodstream. 

There may be other causes of Jaundice in babies. ABO incompatibility, internal bleeding, viral infections,  or liver malfunctions are just a few of the abnormal causes of Jaundice. Each condition will disrupt the conversion process at a different point.  Source: Mattos Lactation. Link: https://www.mattoslactation.com/blog/2018/12/1/answers-to-all-of-your-jaundice-questions-faqs. Field: Hepatology . Disease: Jaundice </s>