When can phototherapy (light therapy) for hyperbilirubinemia be discontinued?

When to Discontinue Phototherapy for Hyperbilirubinemia

Phototherapy for hyperbilirubinemia can be discontinued when the total serum bilirubin (TSB) has declined by 2 to 4 mg/dL below the hour-specific threshold at which phototherapy was initiated. 1

Criteria for Discontinuation Based on Patient Factors

The decision to discontinue phototherapy should consider several key factors:

For Infants Readmitted After Birth Hospitalization

• Discontinue when TSB falls below 13-14 mg/dL 1
• Hospital discharge need not be delayed to observe for rebound 1

Based on Risk Factors

1. Higher Risk Infants (requiring closer follow-up):

   • Gestational age <38 weeks
   • Phototherapy initiated <48 hours of age
   • Positive direct antiglobulin test (DAT)
   • Suspected hemolytic disease

   For these infants:

   • Follow-up TSB measurement 8-12 hours after phototherapy discontinuation
   • Additional TSB measurement on the following day 1
   • Higher risk of rebound hyperbilirubinemia (up to 28% in those with hemolysis or G6PD deficiency) 2

2. Lower Risk Infants:

   • Term infants (≥38 weeks)
   • Phototherapy initiated after 48 hours
   • No evidence of hemolysis

   For these infants:

   • Follow-up TSB within 1-2 days after phototherapy discontinuation 1
   • Lower risk of significant rebound (approximately 8.3% without hemolytic factors) 2

Monitoring After Discontinuation

TSB vs. TcB Monitoring

• TSB should be measured unless it has been ≥24 hours since phototherapy was stopped
• After 24 hours post-phototherapy, transcutaneous bilirubin (TcB) can be used 1
• TcB measurements on patched skin areas during phototherapy show good correlation with serum levels 3

Rebound Assessment

• Most significant rebound occurs within 12-14 hours after discontinuation 4
• Average rebound is less than 1 mg/dL in both term and preterm infants 4
• Infants completing phototherapy who are otherwise healthy may not require follow-up solely to identify rebound 5

Clinical Prediction Rule for Rebound Risk

Three key factors predict the probability of rebound hyperbilirubinemia 6:

1. Gestational age <38 weeks (increases risk 4.7-fold)
2. Younger age at phototherapy initiation (risk decreases by about 50% for each day older)
3. TSB level relative to treatment threshold at phototherapy termination (risk increases 1.5-fold per mg/dL closer to threshold)

Approximately 70% of infants have a <4% probability of rebound hyperbilirubinemia based on these factors 6.

Practical Approach to Discontinuation

1. Determine the threshold at which phototherapy was initiated (based on age, gestational age, and risk factors)
2. Calculate target TSB for discontinuation (2-4 mg/dL below initiation threshold) 1
3. Consider using a higher threshold for discontinuation in low-risk infants to reduce phototherapy duration (can safely reduce treatment time by ~5 hours) 2
4. Plan appropriate follow-up based on risk factors
5. Monitor for rebound according to risk category

Pitfalls to Avoid

• Don't continue phototherapy unnecessarily - this increases hospital stay and separates mother and infant 1
• Don't fail to identify hemolysis - infants with ongoing hemolysis need closer monitoring after discontinuation 1
• Don't use TcB from unpatched skin during phototherapy - it underestimates serum levels by ~3.2 mg/dL 3
• Don't delay discharge just to observe for rebound in low-risk infants 1
• Don't assume all infants have the same rebound risk - use the prediction factors to guide follow-up intensity 6

By following these evidence-based guidelines, clinicians can safely discontinue phototherapy while minimizing both unnecessary treatment and the risk of recurrent hyperbilirubinemia requiring retreatment.