Bilirubin is a yellow pigment that forms when red blood cells break down. In newborns, bilirubin levels tend to be higher than in adults due to their bodies rapidly breaking down red blood cells. The liver is responsible for processing bilirubin, but in newborns, it may take some time for the liver to mature enough to handle this efficiently. This results in elevated bilirubin levels in the early days of life. Understanding what normal serum bilirubin levels are and when intervention is needed is crucial for a newborn’s health.
What Is Bilirubin?
Bilirubin is produced from the breakdown of hemoglobin, a protein found in red blood cells. When red blood cells reach the end of their lifespan, they are broken down in the liver, spleen, and bone marrow. Bilirubin is one of the byproducts of this process. It exists in two forms in the body: direct (conjugated) bilirubin, which is processed by the liver and excreted in bile, and indirect (unconjugated) bilirubin, which is not yet processed by the liver.
In newborns, most of the bilirubin is in the unconjugated form. The liver needs time to mature and become efficient in converting unconjugated bilirubin into a form that can be excreted. Until this happens, bilirubin can build up in the bloodstream, leading to a condition known as jaundice.
Normal Bilirubin Levels in Newborns
For full-term newborns, the normal total serum bilirubin level is typically below 5 milligrams per deciliter (mg/dL) within the first 24 hours of life. However, many newborns experience a temporary rise in bilirubin levels after birth. This rise usually peaks between the third and fifth day of life and then gradually decreases as the liver matures and becomes more efficient at processing bilirubin.
Generally, bilirubin levels are considered normal if they stay below 12 mg/dL in full-term newborns and 15 mg/dL in preterm infants. If levels rise higher than this, it may signal a need for further investigation or treatment.
Why Do Newborns Have Elevated Bilirubin Levels?
Elevated bilirubin levels in newborns are common due to several factors:
Immature Liver Function: A newborn’s liver may not yet be fully developed, which limits its ability to process bilirubin effectively.
Increased Red Blood Cell Breakdown: Newborns have a higher number of red blood cells, and these cells are broken down faster after birth.
Breastfeeding-Related Jaundice: Breastfeeding can sometimes cause higher bilirubin levels due to factors like dehydration or the baby not getting enough milk initially.
Blood Type Incompatibility: When the mother and baby have different blood types, it can lead to increased red blood cell breakdown, raising bilirubin levels.
When Is Bilirubin Too High?
Although elevated bilirubin levels are common, extremely high levels can lead to complications. Bilirubin levels above 20 mg/dL are considered dangerous. If left untreated, very high bilirubin levels can cause a condition known as kernicterus, which can lead to brain damage.
There are specific risk factors that increase the likelihood of severe jaundice, including:
- Prematurity (being born before 37 weeks)
- Blood group incompatibility between mother and baby (e.g., Rh or ABO incompatibility)
- Bruising or cephalohematoma (a collection of blood under the scalp) from birth trauma
- Family history of jaundice
In these cases, bilirubin levels are monitored closely, and treatment may be needed.
Signs of High Bilirubin Levels in Newborns
The most common sign of elevated bilirubin levels is jaundice, a yellowing of the skin and eyes. Jaundice typically starts on the face and then moves down the body. Other signs of high bilirubin levels may include:
- Poor feeding or difficulty breastfeeding
- Lethargy or decreased alertness
- Dark urine (instead of the normal pale color in newborns)
- Pale or clay-colored stools
If any of these symptoms are present, it’s important to consult a healthcare provider.
How Are Bilirubin Levels Tested?
Bilirubin levels can be measured using a blood test or a non-invasive device called a transcutaneous bilirubinometer. The blood test involves taking a small sample from the newborn’s heel (heel prick). A bilirubinometer measures bilirubin by shining light on the baby’s skin and analyzing the reflection. If high levels are detected, the baby may need additional blood tests to confirm the bilirubin levels.
In many hospitals, bilirubin screening is done routinely before a newborn is discharged. If the levels are elevated but not high enough to require immediate treatment, the baby’s bilirubin levels will continue to be monitored after going home.
Treatment for High Bilirubin Levels
If a newborn’s bilirubin levels are too high, treatment is needed to prevent complications. Common treatments include:
Phototherapy: This is the most common treatment for high bilirubin levels. The baby is placed under special blue lights that help break down bilirubin into a form that can be excreted in urine. Phototherapy is safe and effective, and it can be done in the hospital or at home with portable phototherapy devices.
Exchange Transfusion: In rare cases where bilirubin levels are extremely high and phototherapy is not effective, an exchange transfusion may be needed. This involves removing small amounts of the baby’s blood and replacing it with donor blood, which helps remove excess bilirubin.
Adequate Feeding: Breastfeeding or formula feeding frequently can help lower bilirubin levels by promoting the baby’s hydration and bowel movements. This helps flush out bilirubin from the body.
Intravenous Immunoglobulin (IVIg): In cases of blood type incompatibility, intravenous immunoglobulin (a blood product) may be given to reduce the need for an exchange transfusion.
Monitoring and Follow-Up
After treatment, it’s important to continue monitoring bilirubin levels to ensure they return to a safe range. If a baby was treated with phototherapy or other interventions, the healthcare provider will often schedule follow-up visits to check bilirubin levels and monitor the baby’s overall health.
Parents should also continue to observe the baby for signs of jaundice and make sure the baby is feeding well. If the baby is not gaining weight, seems lethargic, or if jaundice worsens, contact the healthcare provider.
Conclusion
Normal bilirubin levels in newborns vary depending on the baby’s age and health. A temporary rise in bilirubin is common and usually harmless. However, high bilirubin levels need to be treated promptly to prevent serious complications. Regular monitoring, early detection, and appropriate treatment can ensure a newborn’s bilirubin levels return to normal and reduce the risk of complications like kernicterus. Understanding the signs of high bilirubin and knowing when to seek help are key for parents in supporting their newborn’s health.
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