Bilirubin is the byproduct of hemoglobin breakdown caused by red blood cell destruction. When red blood cells break down, bilirubin is released into the bloodstream. Unconjugated bilirubin is insoluble and binds to albumin. Since newborns are not readily available to get rid of unconjugated bilirubin, the substance may accumulate in the blood and tissues leading to hyperbilirubinemia.
Jaundice is a characteristic symptom of hyperbilirubinemia. Since bilirubin has a yellow pigmentation, the newborn with excessive bilirubin levels may develop yellowing of the skin, sclera, and nails. The yellowing of the skin usually begins on the face and moves down the body.
Hyperbilirubinemia may lead to the development of kernicterus or bilirubin encephalopathy. Large amounts of bilirubin circulating in the tissues may cause seizures and irreversible brain damage. Symptoms of kernicterus include decreased activity, lethargy, irritability, and hypotonia.
Bilirubin is excreted by binding to the stool. Early and frequent feedings help prevent hyperbilirubinemia by promoting stooling and excretion of bilirubin. Increasing the newborn's scheduled feedings to 8-12 times per day helps prevent hyperbilirubinemia.
Heme oxygenase inhibitors may be used to prevent hyperbilirubinemia in newborns by inhibiting the enzyme that breaks up heme. Examples include tin protoporphyrin and tin mesoporphyrin.
Since bilirubin absorbs light, phototherapy is indicated to decrease bilirubin levels in infants with hyperbilirubinemia. Phototherapy is used throughout the day and the night. The infant is undressed to expose as much skin as possible to the light. However, the genitalia is covered with a diaper and eye protection is worn. During therapy, the infant's fluid intake should be increased to help facilitate the excretion of bilirubin in the urine and stools.
Since the bright light may cause nerve damage to the retina, eye protection is critical for infants with hyperbilirubinemia undergoing phototherapy.
Since phototherapy increases the risk of dehydration, monitoring the newborn's hydration level is critical for maintaining adequate fluid status. Feedings should continue on a regular schedule and may be increased to help increase excretion of bilirubin in the urine and stool. Breastfeeding may be continued and supplemented with expressed breastmilk or formula if the newborn is dehydrated or experiences excessive weight loss.
Monitoring bilirubin levels in newborns with hyperbilirubinemia is critical for detecting increased levels that may lead to complications such as kernicterus. Transcutaneous bilirubinometry (TcB) may be used to assess the newborn's levels of unconjugated bilirubin. Normal levels of unconjugated bilirubin range between 0.2-1.4mg/dl.
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