Neonatal hepatitis is this inflammation of the liver tissue in newborns, usually between 1 and 2 months after birth.
A minority of cases, about 20%, are known to be caused by a virus that infected the infant before birth, through the mother, or maybe shortly after birth.
Several viruses that have been known to cause neonatal hepatitis are rubella, cytomegalovirus, and hepatitis viruses A, B and C.
The other 80% of cases are said to be idiopathic, meaning we don’t really know what the underlying cause was, a lot of times viruses are suspected, but it could also be due to other genetic disorders, cholestasis where bile flow is impaired, or metabolic liver disorders like alpha-1 antitrypsin deficiency.
This last one’s an inherited disease in which the alpha-1 antitrypsin or AAT protein that’s produced in the liver is not quite produced right, and is essentially the wrong shape.
When this happens, it can’t get out of the liver cells, ultimately building up and causing liver cell death, inflammation of liver tissue, and hepatitis.
A newborn or infant with neonatal hepatitis will often have jaundice, causing yellowed skin and eyes due to the blockage or inflammation of the bile ducts.
When these are blocked, bilirubin, a yellow pigmented component of bile, builds up in the blood and starts to get into tissues, causing yellowed skin and eyes.
Bile’s an essential part of fat digestion and absorption of fat soluble vitamins like vitamin A, D, E, and K, so children with neonatal hepatitis and jaundice may fail to gain weight and grow normally due to lack of adequate nutrition.
Bile also functions in removing toxins from the body, like bilirubin but also things like drug metabolites, so if bile flow is reduced, these might deposit and build up in the skin and lead to itching and rashes.
Bilirubin might also be filtered into the urine through the kidneys, causing darker colored urine.