Bilirubin is the end product of heme catabolism formed during a process that involves oxidation-reduction reactions and conserves iron body stores. Unconjugated hyperbilirubinemia is common in newborn infants, but rare later in life. The basic physiology of bilirubin metabolism, such as production, transport, and excretion, has been well described. However, in the neonate, numerous variables related to nutrition, ethnicity, and genetic variants at several metabolic steps may be superimposed on the normal physiological hyperbilirubinemia that occurs in the first week of life and results in bilirubin levels that may be toxic to the brain. Bilirubin exists in several isomeric forms that differ in their polarities and is considered a physiologically important antioxidant. Here we review the chemistry of the bilirubin molecule and its metabolism in the body with a particular focus on the processes that impact the newborn infant, and how differences relative to older children and adults contribute to the risk of developing both acute and long-term neurological sequelae in the newborn infant. The final section deals with the interplay between the brain and bilirubin and its entry, clearance, and accumulation. We conclude with a discussion of the current state of knowledge regarding the mechanism(s) of bilirubin neurotoxicity.

中文翻译：

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新生儿血液，肝，肠和脑处理胆红素的分子生理学和病理生理学。

胆红素是血红素分解代谢的最终产物，该过程在涉及氧化还原反应的过程中形成，并节省了铁体的储存。未结合的高胆红素血症在新生儿中很常见，但在以后的生活中很少见。胆红素代谢的基本生理学，例如生产，运输和排泄，已经得到了很好的描述。但是，在新生儿中，与营养，种族和遗传变异有关的许多变量在几个代谢步骤中可能会叠加在出生后第一周发生的正常生理性高胆红素血症上，并导致可能对大脑有毒的胆红素水平。胆红素以极性不同的几种异构形式存在，被认为是一种重要的生理抗氧化剂。在这里，我们回顾了胆红素分子的化学及其在体内的代谢，重点关注了影响新生婴儿的过程，以及与大龄儿童和成年人之间的差异如何导致急性和长期神经系统疾病的风险新生儿后遗症。最后一部分讨论大脑与胆红素之间的相互作用及其进入，清除和蓄积。我们以关于胆红素神经毒性机制的当前知识状态的讨论作为结束。最后一部分讨论大脑与胆红素之间的相互作用及其进入，清除和蓄积。我们以关于胆红素神经毒性机制的当前知识状态的讨论作为结束。最后一部分讨论大脑与胆红素之间的相互作用及其进入，清除和蓄积。我们以关于胆红素神经毒性机制的当前知识状态的讨论作为结束。