At what level of hyperbilirubinemia should a 3 or 4 day old neonate undergo phototherapy?

From the Guidelines

For a 3 or 4 day old neonate, phototherapy is recommended when the total serum bilirubin (TSB) level reaches the threshold based on gestational age, neurotoxicity risk factors, and age of the infant in hours, as outlined in the latest guidelines from Pediatrics 1. The specific thresholds for phototherapy may vary depending on the infant's risk factors, including prematurity, ABO or Rh incompatibility, G6PD deficiency, and other hemolytic conditions.

• Key considerations for implementing phototherapy include:
  • Using total serum bilirubin (TSB) as the definitive diagnostic test to guide interventions 1
  • Measuring TSB if the transcutaneous bilirubin (TcB) reading is within 3.0 mg/dL of the phototherapy treatment threshold, or if the TcB exceeds the phototherapy treatment threshold 1
  • Evaluating the underlying cause of hyperbilirubinemia in infants who require phototherapy, including measuring glucose-6-phosphate dehydrogenase enzyme activity in infants with jaundice of unknown cause 1
• To implement phototherapy, the following steps can be taken:
  1. Use intensive phototherapy at the recommended thresholds based on gestational age, neurotoxicity risk factors, and age of the infant in hours 1
  2. Monitor the infant's TSB levels to verify efficacy after starting phototherapy, with timing guided by the TSB trajectory and infant age 1
  3. Consider discontinuing phototherapy when the TSB has declined by 2 to 4 mg/dL below the hour-specific threshold at the initiation of phototherapy, taking into account individualized factors such as the cause of hyperbilirubinemia and risk of rebound hyperbilirubinemia 1

From the Research

Phototherapy Thresholds for Neonates

The decision to initiate phototherapy in neonates depends on various factors, including the level of hyperbilirubinemia, gestational age, and the presence of risk factors for bilirubin encephalopathy.

• According to the study by 2, bilirubin toxicity is rare in term babies without hemolysis, and treatment should be deferred to relatively high levels of serum bilirubin, with a goal of keeping bilirubin levels below 23.4 to 29.2 mg/dL.
• The American Academy of Pediatrics guidelines, as referenced in the study by 3, provide thresholds for phototherapy based on the infant's age, gestational age, and bilirubin level.
• However, the study by 3 also notes that the number needed to treat with phototherapy varies considerably across different infant subgroups, ranging from 10 to 3,041, depending on factors such as gestational age, birth weight, and the presence of a positive direct antiglobulin test.

Risk Factors and Phototherapy

The presence of risk factors, such as hemolysis or G6PD deficiency, can affect the decision to initiate phototherapy and the threshold for treatment.

• The study by 4 found that infants with hemolysis or G6PD deficiency were more likely to require re-phototherapy, and that phototherapy duration may be shortened by using higher TSB limits for interruption.
• The study by 5 notes that aggressive phototherapy may reduce peak serum bilirubin and profound impairment, but may also increase deaths among the smallest infants, highlighting the need for careful consideration of the risks and benefits of phototherapy in high-risk populations.

Gestational Age and Phototherapy

Gestational age is an important factor in determining the threshold for phototherapy.

• The study by 6 found that prophylactic phototherapy may be beneficial in preterm or low birth weight infants, but that further studies are needed to determine the efficacy and safety of prophylactic phototherapy on long-term outcomes.
• The study by 5 notes that phototherapy may be effective in reducing peak serum bilirubin and profound impairment in extremely low-birth-weight infants, but that the risk/benefit ratio must be carefully considered in this high-risk population.