newborns have increased rates of bilirubin production due to RBC's with shorter life spans, and a decreased rate of bilirubin elimination due to decreased ability of the neonatal liver to conjugate bilirubin
about 60% of newborns will become clinically jaundiced
bilirubin levels peat at 4 days of life, and may not decline before day 7
admission and treatment should be considered urgently when serum total bilirubin >25mg/dL, with exchange transfusion if it is >30mg/dL or the infant has signs of kernicterus
there are nomograms which plot the bilirubin level according to the infant's age in hours to determine if an infant is at risk for being at toxic levels
the most common pathologic etiologies are due to increased bilirubin production: blood-group incompatibilities, RBC-enzyme deficiency, and RBC structural defects
when jaundice occurs between days 4-7, strongly consider sepsis, UTI, congenital infection (syphilis, CMV, etc)
