New Ratio May Predict Jaundice Risk
Researchers are proposing the total bilirubin/albumin ratio as a practical tool for identifying newborns at higher risk for bilirubin toxicity. A study in *Pediatric Research* examined the clinical utility of this ratio in assessing risk. If adopted, it could help guide earlier and more targeted interventions for neonatal jaundice.
While about 60% of term newborns develop jaundice, severe hyperbilirubinemia that can lead to brain damage is a much rarer event. The central nervous system damage from excess bilirubin, known as kernicterus, is a rare but serious complication of untreated jaundice in babies. This condition can cause permanent neurological issues, including cerebral palsy, hearing loss, and developmental delays. The American Academy of Pediatrics (AAP) updated its clinical practice guidelines for managing hyperbilirubinemia in newborns 35 weeks' gestation or older in 2022. These guidelines recommend universal bilirubin screening for all newborns before hospital discharge, using either a transcutaneous (through the skin) or a total serum bilirubin test. This systematic approach aims to identify infants at risk for severe hyperbilirubinemia early. The neurotoxicity of bilirubin is linked to the "free" or unbound portion of unconjugated bilirubin, which can cross the blood-brain barrier. Albumin, a protein in the blood, binds to bilirubin, and when albumin levels are low, more free bilirubin is available to potentially cause neurological damage. The bilirubin-to-albumin ratio is therefore considered a helpful tool in assessing the risk of bilirubin-induced neurologic dysfunction. A higher total bilirubin to albumin ratio has been associated with an increased risk of bilirubin encephalopathy in newborns. One study found that a higher ratio increased the risk of this condition by 23%. This ratio provides a more accurate risk assessment than total serum bilirubin alone, especially in preterm infants or those with low albumin levels. Risk factors for developing severe hyperbilirubinemia include gestational age less than 38 weeks, the presence of jaundice within the first 24 hours of life, a family history of jaundice requiring phototherapy, and exclusive breastfeeding with suboptimal intake. Certain inherited blood disorders, such as G6PD deficiency, and blood group incompatibility between the mother and baby also increase the risk. Current treatments for high bilirubin levels primarily involve phototherapy, which uses light to change the shape and structure of bilirubin molecules so they can be excreted. In severe cases, an exchange transfusion may be necessary to rapidly decrease bilirubin concentrations. The updated AAP guidelines provide new, higher thresholds for initiating phototherapy based on gestational age and neurotoxicity risk factors.
