Bilirubin is a yellow substance produced when old red blood cells break down. Hemoglobin is released and converted into bilirubin, primarily in the liver. The liver processes bilirubin, making it water-soluble for removal through stool.
When bilirubin builds up faster than the liver can process it, it accumulates in the skin and eyes, causing jaundice (a yellowish discoloration). Jaundice is a common condition in newborns, appearing in half of all infants. While often normal and temporary as a baby’s liver matures, monitoring bilirubin levels is routine newborn care.
Defining the Rate of Rise
The “rate of rise” of bilirubin refers to how quickly bilirubin levels increase in a baby’s blood over time. It is measured in milligrams per deciliter per hour (mg/dL/hour) or per day (mg/dL/day). A rise greater than 0.2 mg/dL per hour or 5 mg/dL per day can signal a serious issue.
Healthcare providers monitor this rate, not just the total bilirubin level, as a rapid increase indicates a problem needing prompt attention. This helps predict if bilirubin will reach concerning levels and guides intervention. Bilirubin levels are measured through total serum bilirubin (TSB) tests.
Causes of a Rapid Increase
A rapid increase in bilirubin levels indicates pathological jaundice, distinct from the slower, physiological jaundice seen in most newborns. One common cause is blood group incompatibility between the mother and infant, such as ABO or Rh incompatibility. Here, the mother’s antibodies can cross the placenta and attack the baby’s red blood cells, leading to rapid destruction and increased bilirubin.
Inherited conditions, like glucose-6-phosphate dehydrogenase (G6PD) deficiency, also cause rapid breakdown of red blood cells. This enzyme deficiency makes red blood cells more susceptible to damage, resulting in hemolysis and a rise in bilirubin. Significant bruising from birth, such as a cephalohematoma (a collection of blood under the scalp), also contributes. This occurs as red blood cells break down internally, releasing bilirubin.
Certain infections, including blood infections (sepsis) or other viral or bacterial infections, trigger a rapid bilirubin increase. These infections can cause increased red blood cell destruction or impair the liver’s ability to process bilirubin efficiently. Other factors, like polycythemia (an excess of red blood cells) or liver conditions, also contribute to a rapid rise.
Associated Health Risks
When bilirubin levels rise too high, there is a risk of it crossing into the brain, damaging the brain. This can lead to acute bilirubin encephalopathy, the short-term effects of bilirubin toxicity on the brain. Symptoms may include sleepiness, poor feeding, a high-pitched cry, or muscle stiffness with arching of the back.
If acute bilirubin encephalopathy is not promptly addressed, it can progress to kernicterus. Kernicterus is severe, permanent brain damage caused by bilirubin deposition in specific brain regions, such as the basal ganglia. This irreversible damage can result in long-term neurological problems, including a type of cerebral palsy characterized by involuntary movements, hearing loss, and issues with eye movement. Medical monitoring is important to prevent bilirubin from reaching harmful levels.
Medical Interventions and Management
Medical interventions are available to manage rapidly rising bilirubin levels and prevent serious complications. Phototherapy is a common and effective treatment. This therapy involves placing the baby under special blue-green lights, often around 480 nanometers.
The light energy works by changing the shape of bilirubin molecules in the baby’s skin through a process called photoisomerization. These altered bilirubin molecules become water-soluble and are then excreted through urine and stool, bypassing the liver’s immature processing. Phototherapy can be intensified by increasing the light’s irradiance, decreasing the distance between the light and the baby, or increasing the surface area of the baby exposed to the light.
In severe cases, when phototherapy is insufficient or bilirubin levels are extremely high, an exchange transfusion may be performed. This procedure involves gradually removing small amounts of the baby’s blood and replacing it with donor blood. Exchange transfusion helps to quickly reduce bilirubin levels and remove antibodies that might be causing red blood cell destruction. While phototherapy has reduced the need for this invasive procedure, it remains an option for challenging cases.