Related Experiment Video
Updated: May 21, 2025

Transcutaneous Microcirculatory Imaging in Preterm Neonates
Published on: December 31, 2015
Factors Affecting the Relationship Between Total and Unbound Bilirubin in Preterm and Term Infants
Thomas Hegyi1, Dalya Chefitz1, Alan Weller1
1Division of Neonatology, Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers, the State University of New Jersey, New Brunswick, New Jersey, USA.
Aim:
Newborn infants universally experience jaundice, most of which is physiologic, but in some high-risk situations, it may lead to neurological dysfunction or death. Unbound bilirubin (Bf) may be the best predictor of bilirubin toxicity in this population. The goal of the study is to examine the relationship between total serum bilirubin (TSB) and Bf and the influencing factors.
Methods:
To calculate the relationship of Bf to TSB, we created a ratio (R) Bf/TSB × 106 to allow the comparison of products with varied concentrations. We then applied it to simultaneously obtain TSB and Bf measurements in infants to examine the influence of prematurity, haemolysis, feeding (breast or bottle feedings) and phototherapy. We also examined R at potential toxic Bf levels in the preterm group.
Results:
The population consisted of 170 term and 130 preterm infants. The R was 3.64 ± 1.08 (SD) in term and 15.18 ± 9.8 in preterm infants. Prematurity and high TSB that required phototherapy significantly increased R. Higher R-values were seen at higher Bf toxic threshold levels.
Conclusion:
An R-value can reflect the relationship between Bf and TSB. The values are greater in prematurity and in infants with high TSB, which requires phototherapy.
Related Concept Videos
Factors Affecting Protein-Drug Binding: Patient-Related Factors
Age stands as a key determinant in protein-drug binding. Neonates, characterized by low albumin content, experience heightened concentrations of unbound drugs such as phenytoin and...
Drug Distribution: Plasma Protein Binding
Factors Affecting Drug Distribution: Miscellaneous Factors
Age plays a significant role due to differences in body composition among different age groups. Infants, for instance, have a higher proportion of total body water and lower albumin levels, a protein that binds drugs in the bloodstream. This unique composition in infants enhances the...
Hepatic Drug Clearance: Effect of Protein Binding
For low-extraction-ratio drugs that are less than 80% protein-bound, minor changes in protein binding...
Factors Affecting Protein-Drug Binding: Drug Interactions
Displacement interactions can have varying outcomes, ranging from toxicity to virtually...
Factors Affecting Protein-Drug Binding: Drug-Related Factors
One crucial factor in drug-protein binding is the drug's lipophilicity or its affinity for fat. More lipophilic drugs tend to have higher binding extents. For example, highly lipophilic drugs like cloxacillin exhibit substantial protein binding, with as much as 95% of the drug binding to proteins. In...

