What sets the threshold
The AAP 2022 thresholds are hour-specific curves that rise over the first days of life and then level off. Each gestational age from 35 to 40 weeks or more has its own curve, and later gestation gives a higher threshold. A separate, lower set of curves applies when any neurotoxicity risk factor is present; those curves use 38 weeks for every infant born at 38 weeks or later.
Use total serum bilirubin; do not subtract the direct fraction. The guideline covers infants born at 35 weeks or more and ends at 14 days. Under 35 weeks, use your NICU's preterm thresholds.
Neurotoxicity risk factors
Gestational age under 40 weeks is itself built into the curves. These additional risk factors switch to the lower curves:
- Albumin below 3.0 g/dL
- Isoimmune hemolysis: positive DAT, ABO or Rh disease
- G6PD deficiency or other hemolysis (a high end-tidal CO, if measured, suggests hemolysis)
- Sepsis
- Significant clinical instability in the past 24 hours
Phototherapy thresholds at 24, 48, 72 and 96 hours
These values (mg/dL) are read from the calculator's embedded AAP 2022 threshold data. Use the calculator for any other hour.
| Gestational age | Risk factor | 24 h | 48 h | 72 h | 96 h |
|---|---|---|---|---|---|
| 35 weeks | None | 10.6 | 14.2 | 16.8 | 18.6 |
| 37 weeks | None | 11.7 | 15.4 | 18.1 | 20.0 |
| 38 weeks | None | 12.3 | 16.0 | 18.8 | 20.7 |
| 39 weeks | None | 12.8 | 16.6 | 19.5 | 21.5 |
| 40 weeks or more | None | 13.3 | 17.0 | 19.8 | 21.8 |
| 35 weeks | Any | 8.9 | 12.2 | 14.6 | 16.1 |
| 37 weeks | Any | 10.0 | 13.5 | 16.1 | 17.9 |
| 38 weeks or more | Any | 10.5 | 14.0 | 16.6 | 18.2 |
Escalation of care and exchange transfusion
Above the phototherapy curve sit two more lines. The exchange transfusion threshold also depends on gestational age, hour of life and risk factors; the risk-factor exchange curve is also used when bilirubin is rising despite phototherapy. The escalation-of-care threshold is 2 mg/dL below the exchange threshold.
At or above escalation: send STAT total and direct bilirubin, CBC, albumin, chemistries and type and crossmatch; give IV hydration and emergent intensive phototherapy; call neonatology for transfer to a NICU that can do an exchange; repeat TSB at least every 2 hours. IVIG 0.5–1 g/kg over 2 hours is for isoimmune hemolysis with a positive DAT. Any sign of acute bilirubin encephalopathy (hypertonia, arching, retrocollis or opisthotonos, high-pitched cry, recurrent apnea) needs an urgent exchange whatever the level.
Transcutaneous bilirubin and rate of rise
Treatment decisions use TSB. Measure a TSB when the TcB is within 3 mg/dL of the phototherapy threshold, above it, or 15 mg/dL or more.
A rise of 0.3 mg/dL per hour or more in the first 24 hours, or 0.2 mg/dL per hour after that, suggests hemolysis. Get a DAT if not done and consider G6PD testing.
Starting, stopping and follow-up
Above the threshold, start intensive phototherapy, repeat TSB within 12 hours, keep feeding and do not give water or dextrose water. Stop when TSB is at least 2 mg/dL below the threshold at the hour phototherapy started. Check for rebound 6–12 hours after stopping and the next day if phototherapy began before 48 hours, the DAT was positive or there was hemolysis; otherwise the next day.
Below the threshold, follow-up depends on how far below: within 2 mg/dL, repeat TSB in 4–8 hours under 24 hours of age or 4–24 hours after; 2 to under 3.5 mg/dL below, TSB or TcB in 4–24 hours; 3.5 to under 5.5 mg/dL below, in 1–2 days.
Use the free tool
Hour-specific phototherapy, escalation and exchange thresholds for 35 weeks or more, with discharge follow-up.
Open Neonatal Jaundice →Common questions
Do neurotoxicity risk factors change the phototherapy threshold?
Yes. Albumin below 3.0 g/dL, isoimmune hemolysis, G6PD deficiency or other hemolysis, sepsis, or significant instability in the past 24 hours move the infant to a lower set of curves. At 48 hours in a 38-week infant, the threshold drops from 16.0 to 14.0 mg/dL.
What is the escalation-of-care threshold?
It is 2 mg/dL below the hour-specific exchange transfusion threshold. Reaching it triggers STAT labs, IV hydration, emergent intensive phototherapy, transfer to a NICU that can do an exchange, and TSB at least every 2 hours.
When should a TcB be confirmed with a serum bilirubin?
Measure a TSB when the TcB is within 3 mg/dL of the phototherapy threshold, above the threshold, or 15 mg/dL or more.
When can phototherapy be stopped?
When TSB is at least 2 mg/dL below the threshold at the hour phototherapy was started. Check for rebound 6–12 hours later and the next day if it began before 48 hours, the DAT was positive or there was hemolysis.
Sources
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. Thresholds are taken hour by hour from its Supplemental Tables 1–4; next steps follow its key action statements and Figure 7.
For education only, not medical advice. Always confirm against current guidelines and your local protocols. Pedemy is independent and not affiliated with or endorsed by the organizations cited.