Phototherapy Thresholds for Neonatal Hyperbilirubinemia

Key Principles

• The American Academy of Pediatrics recommends phototherapy initiation based on hour-specific total serum bilirubin thresholds that vary by gestational age, postnatal age in hours, and the presence of neurotoxicity risk factors 1, 2
• Total serum bilirubin must be used as the definitive diagnostic test to guide all phototherapy decisions, with transcutaneous bilirubin adequate for screening but not accurate enough for treatment decisions 1, 2

Phototherapy Thresholds

• Infants ≥38 weeks gestation have higher phototherapy thresholds than preterm infants 1, 2
• The presence of neurotoxicity risk factors, such as positive direct antiglobulin test, G6PD deficiency, asphyxia, lethargy, temperature instability, sepsis, acidosis, and albumin <3.0 g/dL, lowers the phototherapy threshold 5, 6, 3

Critical Action Thresholds

• A total serum bilirubin level ≥25 mg/dL is a medical emergency requiring immediate admission for intensive phototherapy 5, 6
• Infants with isoimmune hemolytic disease require more aggressive treatment 5, 6

Identifying Hemolysis

• A rapid rate of rise in total serum bilirubin, ≥0.3 mg/dL per hour in the first 24 hours or ≥0.2 mg/dL per hour thereafter, is suggestive of ongoing hemolysis 1, 2, 3
• If total serum bilirubin does not fall or continues to rise despite intensive phototherapy, hemolysis is very likely occurring 5, 6

Discontinuing Phototherapy

• Phototherapy can be stopped when total serum bilirubin has declined by 2-4 mg/dL below the hour-specific threshold at which it was initiated 1, 4
• For high-risk infants, follow-up total serum bilirubin should be obtained 8-12 hours after discontinuation and again the following day 1, 4