Neonatal hyperbilirubinemia, or newborn jaundice, is a very common condition observed shortly after birth. This occurs when excess bilirubin, a yellow pigment, accumulates in a baby’s blood, leading to the characteristic yellow discoloration of the skin and eyes. It is typically a temporary occurrence as newborns adjust to life outside the womb.
Causes of High Bilirubin in Newborns
Bilirubin is a natural byproduct formed when old red blood cells break down. In adults, the liver processes this bilirubin for removal. Newborn livers, however, are still developing and less efficient at processing it, leading to its accumulation. Additionally, newborns have a higher concentration of red blood cells with a shorter lifespan, resulting in increased bilirubin production.
Physiologic jaundice is the most common type, a normal, temporary response as a baby’s liver develops. It typically appears 24-72 hours after birth, peaks around day 4-5 for full-term infants, and resolves within 10-14 days. This form affects 60-80% of healthy infants.
Pathologic jaundice is less common and can indicate a more serious underlying issue. Breastfeeding jaundice, also known as suboptimal intake hyperbilirubinemia, can occur in the first week of life if a baby does not consume enough breast milk, leading to reduced bilirubin elimination. Another type is breast milk jaundice, which typically appears later in the first week, peaks around the second week, and can persist for several weeks or even months. This condition is linked to substances in the mother’s milk that interfere with bilirubin processing.
More concerning causes of elevated bilirubin include blood type incompatibilities, such as ABO or Rh incompatibility, between the mother and baby. The mother’s immune system may produce antibodies that attack the baby’s red blood cells, causing them to break down rapidly. This accelerated destruction of red blood cells significantly increases bilirubin production. Other less common pathologic causes can involve genetic conditions, infections, or problems with the baby’s liver.
Signs and Potential Complications
The most recognizable sign is yellowing of the skin and eyes, known as icterus. This discoloration typically starts on the face and head, then spreads downwards as bilirubin levels rise. Parents can check by gently pressing on the baby’s skin; if the pressed area appears yellow when released, it suggests jaundice.
Beyond the visible yellowing, other signs might suggest higher bilirubin levels or indicate a need for medical attention. These can include unusual sleepiness or lethargy, making the baby difficult to wake for feedings. Babies might also show signs of poor feeding, such as not latching well or having a weak suck. A high-pitched cry or unusual arching of the back can also be indicators that warrant immediate evaluation.
Most newborn jaundice cases are mild and resolve without complications. However, very high and untreated bilirubin levels can lead to kernicterus, a rare but severe condition. Kernicterus occurs when unconjugated bilirubin crosses the blood-brain barrier and deposits in the brain tissue, potentially causing permanent neurological damage. The specific bilirubin level that causes kernicterus is not definitively known, but it has traditionally been associated with levels around 20 mg/dL in full-term infants, with lower thresholds for preterm or sick infants. Early recognition and appropriate treatment are highly effective in preventing this serious complication.
Diagnostic Methods
Diagnosis typically begins with a visual assessment by a healthcare provider. Nurses and doctors routinely check newborns for jaundice by observing their skin and eye color. This initial check helps determine if further testing is needed.
The transcutaneous bilirubinometer (TcB) is a common screening tool. This non-invasive device is gently pressed against the baby’s skin, usually on the forehead or sternum, to estimate bilirubin levels. The TcB helps identify babies who may need more definitive testing.
For a precise diagnosis and to determine severity, a blood test measures the total serum bilirubin (TSB) level. This involves taking a small blood sample, often from the heel. The TSB result, combined with the baby’s age and risk factors like prematurity or feeding difficulties, guides treatment decisions.
Standard Treatment Protocols
Phototherapy, or “bili lights,” is the primary treatment. This therapy exposes the baby’s bare skin to specific wavelengths of blue or green light. The light changes bilirubin molecules, making them water-soluble through a process called photoisomerization. This altered bilirubin is then more easily excreted through urine and stool, bypassing the immature liver’s limitations.
During phototherapy, babies are typically placed under special lights, either in an incubator or on a fiberoptic blanket, while their eyes are protected with patches. Maintaining adequate hydration and nutrition is also an important aspect of treatment. Frequent feedings, whether breastfeeding or formula feeding, help to increase bowel movements, which aids in flushing bilirubin out of the baby’s system more quickly. Healthcare providers often monitor bilirubin levels regularly during phototherapy to ensure the treatment is effective and levels are decreasing.
In rare, severe cases where bilirubin remains extremely high despite intensive phototherapy, an exchange transfusion may be required. This involves slowly removing and replacing small amounts of the baby’s blood with donor blood. The new blood contains normal red blood cells and no bilirubin, rapidly lowering the overall level. This uncommon procedure is reserved for kernicterus risk or when other treatments fail.