HesapHanem

Bilirubin Risk Zone Calculator

Enter the total serum bilirubin and the baby's age in hours to estimate the jaundice risk zone.

Result

High-intermediate risk
10.76 mg/dL
-0.76 mg/dL

How it is calculated

The tool uses a simplified straight-line stand-in for the 95th-percentile curve, not the real clinical nomogram: threshold = min(20, 5 + 0.16 × age), with the bilirubin (tsb) in mg/dL and age in hours. The line stops rising at 20 mg/dL, reached at about 94 hours. The ratio tsb / threshold then sets the zone: above 1.0 High risk, 0.80 to 1.0 High-intermediate, 0.60 to 0.80 Low-intermediate, below 0.60 Low. The margin shown is tsb − threshold, with a plus sign when at or above it. Both inputs must be above zero. It is an educational estimate and not medical advice; a result must not replace a clinician's reading of the real chart.

Worked example

A baby is 36 hours old with a total serum bilirubin of 10 mg/dL. Threshold: 5 + 0.16 × 36 = 5 + 5.76 = 10.76 mg/dL, below the 20 mg/dL cap. Ratio: 10 / 10.76 ≈ 0.93, which falls in the 0.80 to 1.0 band, so the zone is High-intermediate risk. Margin: 10 − 10.76 = -0.76 mg/dL, meaning the reading is just under the threshold line.

Try this example →

Common mistakes

  • Entering the baby's age in days. The field is in hours, so 2 days must be typed as 48; typing 2 gives a threshold of only 5.32 mg/dL and a misleading High risk.
  • Entering bilirubin in µmol/L. The field is mg/dL; divide µmol/L by about 17.1 first, or the value will look many times too high.
  • Treating the zone as a diagnosis. The line is a linear approximation, so zones can differ from the real nomogram, and the tool ignores gestational age and risk factors.
  • Assuming a Low risk zone means no follow-up is needed. A single reading says nothing about how fast bilirubin is rising.

Sources

About this calculator

Neonatal jaundice — yellowing of a newborn's skin from elevated bilirubin — is extremely common and usually harmless, but doctors track it against age-in-hours because bilirubin that's high too early carries more risk than the same level reached later. Clinicians traditionally plot total serum bilirubin against the baby's age in hours on a nomogram (such as the Bhutani nomogram) to sort readings into risk zones — low, low-intermediate, high-intermediate, and high risk of significant hyperbilirubinemia.

This calculator uses a simplified linear approximation of that age-versus-bilirubin relationship to estimate which risk zone a reading falls into. It illustrates how the same bilirubin number can mean different things at 12 hours old versus 72 hours old — but it is a simplified educational estimate, not medical advice, and any real newborn bilirubin concern should be evaluated by a pediatrician using the actual clinical nomogram and lab-grade testing. This tool does not use the real Bhutani percentile curves but a simplified straight line (5 + 0.16 × age in hours, capped at 20 mg/dL) for the 95th percentile, and the 2022 AAP guideline now manages jaundice with gestational-age-specific phototherapy thresholds rather than risk zones, so it is a simplified screening aid; use the clinical nomogram or AAP thresholds for decisions.

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Comments (1)

  • Editorial team

    The age that matters is hours since birth at the moment the blood was drawn, not the baby's age when you happen to look at the result. This page draws a straight line that flattens at 20 mg/dL after about 94 hours, so it is only a rough stand-in. Treat any zone on screen as a prompt to compare with the hour-specific chart your clinic uses and to talk to the baby's doctor. Which nomogram would you want to see here?

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