Neonatal Jaundice: Phototherapy and Bilirubin Monitoring

Neonatal jaundice is common, but a yellow appearance alone cannot show how much bilirubin is circulating or whether treatment is needed. Most newborns have temporary, unconjugated hyperbilirubinemia caused by increased red-cell turnover and an immature liver. A smaller group develops rapidly rising levels, hemolysis, infection, or liver disease and requires urgent assessment.

Safe care depends on combining the infant’s age in hours, gestational age, bilirubin concentration, feeding pattern, clinical condition, and risk factors for bilirubin neurotoxicity. Phototherapy is highly effective when used at the appropriate threshold, while unnecessary treatment can disrupt feeding, bonding, sleep, and family confidence.

The educational material preserved through the FAOPS 2020 congress site reflects the wider importance of neonatal and perinatal research across Asia and Oceania. Although the Tokyo meeting was canceled in 2020 because of the COVID-19 pandemic, its clinical themes remain relevant to everyday newborn care.

Why Bilirubin Matters

Bilirubin is produced when hemoglobin is broken down. Unconjugated bilirubin travels to the liver attached to albumin, where it is processed and excreted into bile. In newborns, high production, limited hepatic conjugation, and increased intestinal reabsorption can cause levels to rise during the first several days of life.

The main concern is bilirubin crossing into brain tissue. Acute bilirubin encephalopathy may present with poor feeding, lethargy, abnormal tone, a weak or high-pitched cry, arching, or seizures. Severe untreated toxicity can result in chronic neurologic injury, including the movement and hearing disorders associated with kernicterus.

Visual inspection is useful for prompting evaluation but is an unreliable method for estimating severity, particularly in infants with darker skin tones or under variable lighting. Any infant who appears jaundiced should be assessed in context, and a bilirubin measurement should be obtained when the clinical appearance, age, or risk profile warrants it.

Assessing Risk Early

The first step is to establish the infant’s age in hours and gestational age accurately. Bilirubin values must be plotted against an age-specific treatment graph rather than interpreted as isolated numbers. A concentration that is acceptable at 24 hours may be concerning at 72 hours, while the same value may require different action in a preterm or medically unstable infant.

Risk factors for severe hyperbilirubinemia include hemolysis from blood-group incompatibility or glucose-6-phosphate dehydrogenase deficiency, significant bruising, cephalohematoma, exclusive breastfeeding with poor intake, excessive weight loss, sepsis, and low gestational age. Albumin deficiency and clinical instability can also increase the risk that bilirubin will reach the brain.

Jaundice appearing during the first 24 hours is particularly important. It may indicate hemolysis or another pathologic process and should prompt prompt measurement rather than routine observation. A rapidly rising bilirubin level, often assessed through serial measurements, deserves attention even when the current value remains below the phototherapy line.

Choosing Phototherapy Thresholds

Phototherapy converts bilirubin into water-soluble photoisomers that can be eliminated without normal hepatic conjugation. Treatment should begin according to a validated guideline, such as a national neonatal protocol or an institutionally approved nomogram. Thresholds commonly vary according to gestational age, postnatal age, and the presence of neurotoxicity risk factors.

For infants born at 35 weeks or later, contemporary guidance generally uses hour-specific thresholds and separates babies with no additional risk factors from those with hemolysis, sepsis, albumin deficiency, or clinical instability. Preterm infants often require separate protocols because their vulnerability and treatment targets differ. Clinicians should avoid applying a term-infant graph to a very preterm newborn.

The decision is also shaped by the rate of increase and the reliability of follow-up. An infant approaching the treatment threshold may need repeat testing sooner, feeding support, investigation for hemolysis, or admission for observation. The clinical question of when to treat should never be reduced to skin color or a single universal bilirubin value.

Reading Bilirubin Results Correctly

Transcutaneous bilirubinometry offers a quick, painless screening estimate and can reduce the number of blood samples required. It is useful before discharge and during follow-up, but readings can be affected by skin pigmentation, device type, recent phototherapy, and high bilirubin concentrations. A serum test is required when the result is near the treatment threshold or when the device reading is unexpectedly high.

Total serum bilirubin, or TSB, remains the principal value used for phototherapy decisions. Direct or conjugated bilirubin should be measured when jaundice is prolonged, the infant has pale stools or dark urine, or there are signs of cholestasis or liver disease. Conjugated hyperbilirubinemia is not treated with standard phototherapy and requires a different diagnostic pathway.

A single result provides less information than a trend. Recording the time of each measurement allows clinicians to calculate the approximate rate of rise and compare it with the treatment threshold. Results should be communicated clearly at handover, including the infant’s age in hours, gestational age, feeding status, risk factors, and planned time for reassessment.

Delivering Effective Phototherapy

The effectiveness of phototherapy depends on irradiance, wavelength, exposed surface area, and treatment duration. Blue-green light in the appropriate spectrum is generally used, with the infant positioned so that as much skin as possible receives light. Eye protection must be secure, while the airway and face remain unobstructed.

Nursing care includes checking temperature, hydration, feeding tolerance, stool and urine output, and the condition of the skin. Depending on the infant’s stability and local protocol, short breaks for breastfeeding or expressed milk may be allowed. Sick or preterm babies may need enteral or intravenous fluid plans tailored to their clinical status.

Phototherapy equipment should be checked for distance, lamp function, and irradiance according to manufacturer and hospital procedures. A glowing device does not necessarily provide adequate treatment. Bilirubin should be rechecked at an interval appropriate to the starting level, rate of rise, and risk profile; testing too early may not show the full response, while testing too late can delay escalation.

Treatment may be stopped when the bilirubin has fallen sufficiently below the relevant threshold and the infant is clinically stable. A rebound measurement is often considered for babies treated early, those with hemolysis, and those with other risk factors. Follow-up after discharge should be arranged when rebound or continued bilirubin elevation is plausible.

Feeding, Follow-Up, and Special Situations

Frequent, effective feeding supports stool production and reduces enterohepatic circulation. Families should receive practical help with latch, milk transfer, and expressing milk when necessary. Supplementation decisions should be individualized rather than based on jaundice alone, and breastfeeding should generally continue while bilirubin is monitored and treated.

Home phototherapy may be appropriate for carefully selected infants who are clinically well, near term, feeding adequately, below a defined threshold, and able to receive reliable equipment and daily medical supervision. It is unsuitable when bilirubin is rising rapidly, hemolysis is suspected, follow-up is uncertain, or the infant has signs of illness.

Prolonged jaundice needs a separate assessment. Review feeding and growth, inspect stool and urine color, and measure total and direct bilirubin when the duration exceeds the expected period or clinical features are concerning. A history of infection, endocrine disease, metabolic illness, family conditions, or medication exposure may guide further testing.

Prevention also matters beyond bilirubin treatment. Infection prevention, safe delivery practices, and timely newborn care reduce the burden of neonatal illness overall; related public-health priorities are discussed in prevention strategies for low-resource settings. A well-organized newborn service connects jaundice surveillance with broader maternal and neonatal safety systems.

Practical Recommendations for Clinical Teams

Clear protocols reduce variation between staff members and help families understand why a blood test or admission is needed. Every unit should define how it documents age in hours, bilirubin results, risk factors, treatment thresholds, phototherapy checks, discharge criteria, and post-discharge review.

Useful bedside priorities include:

• Measure bilirubin promptly when jaundice appears in the first 24 hours or seems more marked than expected.
• Use an hour-specific, gestation-appropriate treatment graph rather than a fixed bilirubin cutoff.
• Confirm a transcutaneous result with serum bilirubin when it approaches the treatment threshold or follows phototherapy.
• Assess feeding, weight change, urine, stool, temperature, and hydration at every review.
• Escalate rapidly for neurologic signs, sepsis, a fast bilirubin rise, suspected hemolysis, or a level near exchange-transfusion criteria.

Families should be told what jaundice monitoring involves, which symptoms require urgent help, and when the next bilirubin test or clinical review will occur. Written instructions are particularly valuable after early discharge, when a newborn’s bilirubin may still be rising.

Accurate documentation supports continuity between the birth unit, community midwife, pediatric service, and primary-care team. It should include the time and method of each bilirubin measurement, the treatment threshold used, feeding advice, and the responsible clinician for follow-up.

Well-designed monitoring makes phototherapy a focused intervention rather than a substitute for assessment. When staff combine timely bilirubin testing with feeding support, risk-based thresholds, reliable equipment, and clear escalation pathways, newborns receive protection from bilirubin toxicity while avoiding unnecessary disruption.

Use these principles alongside current national guidance and local neonatal protocols when evaluating a jaundiced infant. Consistent measurement, careful observation, and prompt treatment when indicated remain the foundation of safer newborn care.