Related Experiment Videos
[Light therapy of newborns with hyperbilirubinemia]
1Institutt for Kreftforskning, Det Norske Radiumhospital, Oslo.
Insights
Phototherapy effectively treats newborn jaundice by converting bilirubin into water-soluble products. The most crucial reaction involves irreversible Z-lumirubin formation, a safe and efficient treatment for neonatal hyperbilirubinemia.
Area of Science:
- Biochemistry
- Photochemistry
- Neonatology
Context:
- Neonatal jaundice, caused by bilirubin accumulation, affects a significant fraction of newborns.
- High bilirubin levels pose a risk of irreversible brain damage (kernicterus).
- Phototherapy is a common treatment for neonatal jaundice, used in 5-10% of Norwegian newborns.
Purpose:
- To elucidate the photochemical reactions underlying phototherapy for neonatal jaundice.
- To identify the key reactions responsible for bilirubin degradation and excretion.
Summary:
- Phototherapy utilizes light to induce bilirubin breakdown through photooxidation and isomerization.
- Key reactions include reversible isomer formation and irreversible Z-lumirubin production.
- Z-lumirubin formation, an irreversible process, is considered the primary therapeutic mechanism, with its efficiency increasing with longer wavelengths.
Impact:
- Understanding these photochemical pathways optimizes phototherapy efficacy and safety.
- This knowledge contributes to managing hyperbilirubinemia and preventing kernicterus in newborns.
- Phototherapy's transient side effects underscore its favorable safety profile in neonatal care.
Abstract:
In a significant fraction of newborns the skin becomes yellow for a few days after birth due to accumulation of bilirubin, a product of heme catabolism. If the concentration of bilirubin in the serum approaches the binding capacity of albumin, bilirubin may penetrate into the central nervous system and cause irreversible damage. Phototherapy is the most common form of therapy, used on 5-10% of all newborns in Norway. Three photochemical reactions are of importance in this treatment: Photooxydation of bilirubin followed by fragmentation of the molecule and formation of water-soluble products. Reversible formation of (4Z,15E) and (less important) (4E,15Z) configurational isomers. Irreversible formation of the structure isomer Z-lumirubin, which is relatively water-soluble and can be excreted. The (4E,15Z) isomer is probably an intermediate in the formation of Z-lumirubin, whose formation therefore requires the absorption of two photons. Irreversible formation of Z-lumirubin, which has a quantum yield that increases with increasing wavelength of the light, is believed to be the most important reaction in phototherapy. All known side-effects of phototherapy are transient and not serious.