Neonatal Jaundice: AAP Guidelines, Phototherapy Thresholds, and Bilirubin Nomograms

Summary

• Neonatal jaundice occurs in approximately 60% of term and 80% of preterm infants; most cases are physiologic [1,2].
• The 2022 AAP guideline revision raised phototherapy thresholds for low-risk term infants, based on evidence that neurotoxicity does not occur until concentrations well above the 2004 exchange transfusion thresholds [3].
• Neurotoxicity risk factors (gestational age <38 weeks, albumin <3.0 g/dL, hemolytic disease, sepsis, clinical instability) lower both phototherapy and exchange transfusion thresholds [3,4].
• Escalation of care is defined as TSB reaching a level 2 mg/dL below the exchange transfusion threshold; this triggers NICU-level management [3].
• The bilirubin-albumin (B/A) ratio can supplement TSB in exchange transfusion decisions and correlates with unbound bilirubin, the neurotoxic fraction [5,6].
• Conjugated hyperbilirubinemia at 2 weeks (formula-fed) or 3-4 weeks (breastfed) warrants evaluation for cholestasis, including biliary atresia [3,4].

Physiologic vs. Pathologic Jaundice

Physiologic jaundice reflects normal neonatal physiology: increased red blood cell breakdown, immature hepatic conjugation (only 1% of adult enzyme activity), increased enterohepatic circulation, and low fluid intake in the first days of life [1]. It typically peaks at day 3-5 in term infants and day 5-7 in preterm infants, then gradually resolves.

Features suggesting pathologic jaundice:

• Onset in the first 24 hours of life
• Rapid rate of TSB rise: >0.3 mg/dL/hour in the first 24 hours, or >0.2 mg/dL/hour thereafter
• TSB exceeding the 95th percentile for age on hour-specific nomograms
• Persistence beyond 3-4 weeks
• Direct/conjugated hyperbilirubinemia

Causes include hemolytic disease (ABO/Rh incompatibility, G6PD deficiency), sepsis, cephalohematoma or significant bruising, cholestasis, and metabolic disorders [2,4].

Neurotoxicity Risk Factors

The 2022 AAP guideline defines neurotoxicity risk factors that lower treatment thresholds [3,4]:

• Gestational age <38 weeks (risk increases with each additional week <40 weeks)
• Albumin <3.0 g/dL
• Isoimmune hemolytic disease (positive direct antiglobulin test), G6PD deficiency, or other hemolytic conditions
• Sepsis
• Significant clinical instability in the previous 24 hours

Clinical pearl. Low serum albumin raises neurotoxicity risk because it increases the fraction of unbound bilirubin available to cross the blood-brain barrier. Most laboratories cannot measure unbound bilirubin directly, so albumin <3.0 g/dL is used as a proxy risk factor [3].

Phototherapy

Thresholds

Thresholds are read from hour-specific nomograms based on gestational age and neurotoxicity risk factor status [3]:

Infants <24 hours old with TSB at or above the phototherapy threshold are likely to have a hemolytic process and should be evaluated for hemolytic disease [3].

Look up hour-specific thresholds in AAP Bilirubin 2022 →

Intensive phototherapy is defined as narrow-spectrum LED blue light (460-490 nm wavelength, peak approximately 475 nm) with irradiance ≥30 µW/cm²/nm, applied to as much of the infant's body surface as possible [7]. The goal is to reduce further TSB increases that would require escalation of care, including exchange transfusion.

Home Phototherapy

For infants already discharged who develop TSB above threshold, home phototherapy is an option if all of the following are met [3]:

• Gestational age ≥38 weeks
• ≥48 hours old
• Clinically well with adequate feeding
• No known neurotoxicity risk factors
• No previous phototherapy
• TSB no more than 1 mg/dL above the phototherapy threshold
• LED-based phototherapy device available in the home without delay
• TSB can be measured daily

Caution. Home phototherapy should not be used if there is any concern about device quality, family ability to operate the device, or ability to measure bilirubin daily [3].

Monitoring

TSB is measured to confirm efficacy after starting phototherapy. Timing depends on the rate of TSB rise and infant age. Hospitalized infants are typically checked every 12-24 hours, more frequently if TSB is rising rapidly or approaching escalation-of-

References

1. Par EJ, Hughes CA, DeRico P. Neonatal Hyperbilirubinemia: Evaluation and Treatment. Am Fam Physician. 2023;107(5):525-534.
2. Espinosa K, Brown SR. Hyperbilirubinemia in Newborns: Updated Guidelines From the AAP. Am Fam Physician. 2023;107(6):661-664.
3. Kemper AR, Newman TB, Slaughter JL, et al. Clinical Practice Guideline Revision: Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation. Pediatrics. 2022;150(3):e2022058859.
4. Slaughter JL, Kemper AR, Newman TB. Technical Report: Diagnosis and Management of Hyperbilirubinemia in the Newborn Infant 35 or More Weeks of Gestation. Pediatrics. 2022;150(3):e2022058865.
5. Miyabayashi H, Kubota Y, Hara K, et al. Determinants of Unbound Bilirubin and Clinical Utility of the Total Bilirubin/Albumin Ratio in Neonates. Pediatr Res. 2026. doi:10.1038/s41390-026-04851-6
6. Iwatani S, Hagimoto S, Kobayashi T, et al. Bilirubin-Albumin Molar Ratio for Screening High Unbound Bilirubin Across Gestational Ages. Pediatr Res. 2025. doi:10.1038/s41390-025-04702-w
7. Lai NM, Ahmad Kamar A, Lee SWH, et al. High- Versus Low-Dose Phototherapy for Neonatal Jaundice. Cochrane Database Syst Rev. 2026;3:CD003308.