Bilirubin is a yellowish substance produced when old red blood cells break down. It travels through the bloodstream to the liver, where it is processed and then excreted from the body, primarily in stool. Newborn babies often have higher bilirubin levels because their bodies are rapidly replacing fetal red blood cells, and their immature livers are not yet fully efficient at processing it. This temporary buildup causes neonatal jaundice, which appears as a yellow discoloration of the baby’s skin and the whites of their eyes. While jaundice is a frequent and often harmless condition in newborns, elevated bilirubin levels require careful monitoring.
Measuring Bilirubin Levels
To assess jaundice in newborns, healthcare providers measure bilirubin levels. Two primary methods are used: transcutaneous bilirubin (TcB) screening and total serum bilirubin (TSB) blood tests. TcB uses a bilirubinometer that touches the baby’s skin to estimate bilirubin by analyzing light reflection or absorption. This non-invasive method serves as an effective initial screening tool.
For more precise measurement and confirmation, especially when TcB readings are high or approaching treatment thresholds, a TSB test is performed. This involves taking a blood sample, typically from a heel prick, which is then analyzed in a laboratory. TSB is considered the definitive method for determining bilirubin levels. Bilirubin measurements are commonly reported in milligrams per deciliter (mg/dL) in the United States, though micromoles per liter (µmol/L) is also used, with 1 mg/dL being approximately equivalent to 17.1 µmol/L.
When Phototherapy Becomes Necessary
The decision to begin phototherapy for a newborn with jaundice is not determined by a single bilirubin number alone. It involves a comprehensive evaluation of several interconnected factors. Healthcare providers consider the baby’s exact age in hours since birth, as bilirubin thresholds change rapidly during the first few days of life. The baby’s gestational age at birth is also important, with preterm infants generally requiring phototherapy at lower bilirubin levels than full-term babies.
The presence of risk factors influences the treatment threshold. These can include blood group incompatibility between the mother and baby, which can lead to increased red blood cell breakdown, or significant bruising from a difficult delivery. A rapid rise in bilirubin levels over a short period also indicates a higher risk. Medical professionals refer to clinical guidelines and nomograms, such as those provided by the American Academy of Pediatrics (AAP), to plot the baby’s bilirubin level against their age and risk factors. These charts help determine if the bilirubin level crosses a threshold that necessitates phototherapy, showing it is a dynamic, individualized assessment.
Understanding Phototherapy Treatment
Phototherapy is an effective treatment for reducing bilirubin levels in newborns. This non-invasive procedure uses specialized light to help the baby’s body process bilirubin more efficiently. The most effective light falls within the blue-green spectrum, typically ranging from 460 to 490 nanometers, as these wavelengths can penetrate the skin and are readily absorbed by bilirubin.
Once absorbed, the light converts bilirubin molecules into water-soluble forms called photoisomers. These altered bilirubin molecules can then be excreted from the baby’s body through urine and stool without requiring further processing by the liver. During treatment, the baby is usually undressed, except for a diaper, to maximize skin exposure to the light, and their eyes are covered with protective patches to prevent irritation. Parents can expect the baby’s temperature and bilirubin levels to be monitored regularly throughout treatment, and frequent feeding is encouraged.
After Phototherapy: Monitoring and Care
Once phototherapy is complete or bilirubin levels have decreased sufficiently, ongoing monitoring remains important. Healthcare providers often conduct follow-up bilirubin tests to check for rebound jaundice, a rise in bilirubin levels after treatment has stopped. This is particularly important for babies who had risk factors for elevated bilirubin, such as prematurity or hemolytic conditions.
Parents should continue to observe their baby for any re-yellowing of the skin or eyes, or signs like poor feeding or unusual lethargy, which could indicate a need for further medical evaluation. Ensuring the baby receives adequate nutrition through frequent feedings is important, as this helps promote bowel movements, which are essential for bilirubin excretion. Maintaining open communication with healthcare providers and attending all recommended follow-up appointments helps ensure the baby’s continued health and well-being.