From the Guidelines
Bilirubin is a yellow-orange pigment produced during the normal breakdown of red blood cells in the body, and its levels are crucial for diagnosing and monitoring conditions like liver disease, gallstones, or certain types of anemia, with elevated levels potentially causing jaundice and neurological complications, particularly in newborns 1.
Definition and Production of Bilirubin
Bilirubin is produced when old red blood cells are destroyed, and hemoglobin is broken down into bilirubin, which is then processed by the liver. The liver converts bilirubin into a water-soluble form that can be excreted in bile and ultimately eliminated through stool.
Clinical Significance of Bilirubin
Elevated bilirubin levels in the blood can cause jaundice, a yellowing of the skin and whites of the eyes. This elevation may occur due to increased production of bilirubin, problems with liver function that prevent proper processing, or blockages in the bile ducts that inhibit excretion. Measuring bilirubin levels in blood tests is important for diagnosing and monitoring conditions like liver disease, gallstones, or certain types of anemia.
Bilirubin in Newborns
In newborns, temporary high bilirubin levels are common and may require phototherapy treatment to prevent potential neurological complications. The management of hyperbilirubinemia in newborns involves measuring total serum bilirubin (TSB) levels and using phototherapy or exchange transfusions as needed, with guidelines provided for the treatment of newborns 35 or more weeks of gestation 1.
Key Considerations
- The liver plays a crucial role in processing bilirubin, and any dysfunction can lead to elevated levels.
- Blockages in the bile ducts can also inhibit the excretion of bilirubin, leading to increased levels.
- Measuring bilirubin levels is essential for diagnosing and monitoring various conditions.
- In newborns, phototherapy is a common treatment for high bilirubin levels to prevent neurological complications.
- The decision to initiate phototherapy or perform an exchange transfusion is based on the TSB level, gestational age, and the presence of risk factors for bilirubin neurotoxicity 1.
From the Research
Definition and Function of Bilirubin
- Bilirubin is a major end product of heme breakdown and an important constituent of bile, responsible for its characteristic color 2.
- It is normally glucuronidated and excreted by the liver into bile, and failure of this system can lead to a buildup of conjugated bilirubin in the blood, resulting in jaundice 3.
- Bilirubin is the final product of heme catabolism in the systemic circulation and has been found to have protective effects against various oxidative stress-mediated diseases, including atherosclerotic conditions 4.
Clinical Implications of Bilirubin
- Inherited disorders characterized by impaired bilirubin conjugation or transport can result in various degrees of hyperbilirubinemia, either unconjugated or conjugated 2.
- Disrupted regulation of hepatobiliary transport systems can explain jaundice in many acquired liver disorders 2.
- Mildly elevated bilirubin concentrations have been associated with protection against oxidative stress-mediated diseases, including atherosclerotic diseases, diabetes, metabolic syndrome, and cardiovascular diseases 4, 5, 6.
Biological Properties of Bilirubin
- Bilirubin has been found to have antioxidant properties and may have a beneficial role in preventing oxidative changes in various diseases, including atherosclerosis, cancer, and inflammatory diseases 5.
- The heme catabolic pathway, which produces bilirubin, may have beneficial effects on disease prevention, and therapeutic induction of heme oxygenase may increase bilirubin concentrations and lower the risk of oxidative stress-related diseases 5.
- Bilirubin has been consistently shown to be negatively correlated with cardiovascular diseases and related risk factors, such as arterial hypertension, diabetes mellitus, metabolic syndrome, and obesity 6.