Which thresholds does this use?

It implements the NICE neonatal jaundice treatment thresholds, which give a phototherapy line and an exchange-transfusion line that rise with postnatal age and shift higher with greater gestational maturity. The lines are defined as treatment-threshold graphs for each gestation band.

Why does gestational age change the threshold?

More premature babies have immature livers and blood-brain barriers, so they are at risk of bilirubin toxicity at lower levels. NICE therefore sets lower thresholds for earlier gestations and the highest thresholds at term, so the same bilirubin can be safe at 40 weeks but require treatment at 32.

How are the threshold lines shaped?

Within the first day or two the threshold rises steeply with age in hours, then plateaus to a constant ceiling from roughly day three or four onward. This tool models that as a linear rise from a birth value up to the plateau, matching the NICE graph shape, then a flat line.

What should I do if bilirubin is above the line?

A value at or above the phototherapy threshold indicates phototherapy should be started, and a value reaching the exchange line indicates preparation for exchange transfusion and urgent senior review. Always act on the official NICE chart and local protocol, not a single calculator output.

Is this a replacement for the NICE chart?

No. It is a convenience tool that approximates the published threshold graphs so you can quickly see roughly where a value sits. The definitive decision must be made by plotting on the official age-specific NICE treatment threshold chart and applying clinical judgement.

Neonatal Jaundice Phototherapy Threshold Calculator

In a newborn, the level of bilirubin that warrants treatment is not a single number; it climbs with the baby’s age in hours and is lower for more premature infants. This tool reproduces the shape of the NICE treatment-threshold graphs so you can quickly see where a measured total serum bilirubin sits relative to the phototherapy and exchange-transfusion lines.

How it works

For each gestational-age band, NICE defines two lines that rise over the first days of life and then plateau. This tool models each line as a linear rise from a birth value to a plateau ceiling reached around 96 hours, then constant thereafter:

threshold(age) = birth_value + (plateau - birth_value) x min(age, 96) / 96

Greater gestational maturity raises both the birth value and the plateau, reflecting a higher tolerance for bilirubin. The exchange line always sits above the phototherapy line for the same gestation.

Interpretation and notes

A measured total serum bilirubin at or above the phototherapy line means phototherapy should begin; reaching the exchange line signals urgent senior review and preparation for exchange transfusion. The values used here approximate the published NICE graphs for common gestation bands and are intended only as a quick orientation. The definitive decision must always be made by plotting the value on the official NICE age-specific treatment threshold chart for the exact gestation, alongside clinical assessment and risk factors. This is an educational tool, not a clinical decision system.