Neonatal Bilirubin Thresholds (AAP 2022): Phototherapy and Exchange by Hour and Gestation

What it is

The 2022 AAP clinical practice guideline replaced the 2004 Bhutani-era nomograms with new, slightly higher treatment thresholds for newborns ≥35 weeks’ gestation. Total serum bilirubin (TSB) is plotted against postnatal age in hours, and the line you compare against depends on gestational age and whether neurotoxicity risk factors are present. This calculator returns the phototherapy, escalation-of-care, and exchange thresholds for a given infant and flags where the measured TSB falls.

Method

Three numbers define management at any given hour:

• Phototherapy threshold (AAP Figure 2 / 3) — start intensive phototherapy at or above this TSB.
• Exchange threshold (Figure 4) — emergent exchange transfusion at or above.
• Escalation of care — defined as exchange threshold minus 2 mg/dL; intensive phototherapy plus urgent labs and exchange preparation.

Thresholds rise with gestational age (a 35-week infant is treated more aggressively than a 40-week infant at the same hour) and fall when any neurotoxicity risk factor is present. Per AAP, risk factors are: gestational age <38 weeks, isoimmune hemolytic disease (positive DAT), G6PD deficiency or other hemolysis, albumin <3.0 g/dL, sepsis, or significant clinical instability in the prior 24 hours. The tool defaults to the lower (any-risk) thresholds when risk status is unknown — erring toward treatment.

When to use

Any newborn ≥35 weeks with a measured or transcutaneous-confirmed TSB, to decide phototherapy, when to escalate, and when exchange is indicated. Not for infants <35 weeks.

Worked example

A 36-week infant, 48 hours old, no recognized risk factors, TSB 15.5 mg/dL. The no-risk phototherapy threshold at this point is ~14.8 mg/dL and the exchange threshold ~21.9 mg/dL. 15.5 ≥ 14.8 → phototherapy indicated, comfortably below the escalation zone (~19.9 mg/dL). Recheck TSB on the post-phototherapy interval the guideline specifies.

Pitfalls

• BETA — digitized curves. These thresholds are read off the AAP continuous curves (via PediTools) and hour-interpolated, accurate to roughly ±0.3 mg/dL. The 35–37 week early-hour exchange cells especially should be confirmed against the official AAP figures before acting. This is kernicterus-critical math — verify.
• The AAP decision also permits a bilirubin:albumin ratio criterion for exchange that is not modelled here.
• Use TSB, not transcutaneous bilirubin, for treatment decisions near or above threshold.
• At/above the escalation line: intensive phototherapy plus STAT TSB, DAT, CBC, albumin, and type & cross; IVIG for isoimmune disease; prepare for exchange. Exchange emergently for any sign of acute bilirubin encephalopathy regardless of the number.
• The 2022 thresholds are slightly higher than the 2004 curves — don’t apply old nomograms.

Run it: Neonatal Bilirubin Thresholds (AAP 2022)

Decision support for qualified clinicians only — verify against current primary guidelines and your clinical judgement.