Lumirubin

Chemical structure of Lumirubin

Lumirubin is a water-soluble tetrapyrrole that is formed as a result of the photochemical conversion of bilirubin. It is an important compound in the context of neonatal jaundice treatment, where it is produced during phototherapy.

Formation

Lumirubin is formed when bilirubin, a yellow compound that occurs in the normal catabolic pathway that breaks down heme in red blood cells, is exposed to light. This exposure leads to a structural isomerization of bilirubin, converting it from its native form to lumirubin. The process involves the breaking of intramolecular hydrogen bonds and a change in the configuration of the molecule from a Z,Z-bilirubin to a Z,E-bilirubin, and eventually to lumirubin.

Role in Phototherapy

Phototherapy is a common treatment for neonatal jaundice, a condition characterized by high levels of bilirubin in the blood of newborns. During phototherapy, the skin of the infant is exposed to blue light, which facilitates the conversion of bilirubin into lumirubin. Unlike bilirubin, lumirubin is more water-soluble and can be excreted in the bile and urine without the need for conjugation in the liver. This conversion helps reduce the levels of bilirubin in the blood, alleviating the symptoms of jaundice.

Chemical Properties

Lumirubin, like other tetrapyrroles, is characterized by its ring structure. The conversion from bilirubin to lumirubin involves a change in the double bond configuration, which alters its solubility and excretion properties. The chemical structure of lumirubin is depicted in the adjacent image.

Clinical Significance

The ability of lumirubin to be excreted without conjugation is crucial in the treatment of hyperbilirubinemia in newborns. By reducing bilirubin levels, phototherapy prevents the risk of kernicterus, a form of brain damage that can result from very high levels of bilirubin.

Related Pages

• Bilirubin
• Phototherapy
• Neonatal jaundice
• Kernicterus