According to the American Pregnancy Association, serum bilirubin levels that exceed 10 milligrams at under 24 hours after birth, above 15 milligrams at 24 to 48 hours after birth, above 18 milligrams at 49 to 72 hours after birth and above 20 milligrams after 72 hours beyond birth require treatment. Any range below these levels is considered healthy and normal.
KidsHealth notes that high serum bilirubin levels indicate newborn jaundice, which has symptoms that include the yellowing of eyes and skin, difficulty feeding and excessive sleepiness. When jaundice is left untreated and serum bilirubin levels exceed 25 milligrams, there is a risk of brain damage, cerebral palsy and deafness.
According to KidsHealth, mild and moderate cases of jaundice typically resolve on their own at one to two weeks of age, as the body expels bilirubin through bowel movements. Frequent feedings or supplementation with formula help to speed up the process. For high levels of bilirubin, phototherapy is used to alter the bilirubin within the baby's body and make it easier to expel. A newborn may be readmitted to the hospital to treat high levels of bilirubin in the blood, and in rare cases, a blood exchange may be necessary to remove the bilirubin from the blood.