From the Guidelines
Phototherapy has a minimal effect on direct bilirubin levels, and its use should not be considered a primary treatment for direct hyperbilirubinemia. The primary mechanism of phototherapy is to convert indirect bilirubin into water-soluble isomers that can be excreted without liver conjugation, which does not significantly impact direct bilirubin levels 1. Direct bilirubin is already water-soluble and can be eliminated in urine and stool without requiring the photo-isomerization process.
Key Considerations
- The presence of direct hyperbilirubinemia should not be considered a contraindication to phototherapy, particularly in sick neonates 1.
- However, the efficacy of phototherapy may be decreased in infants with cholestasis, as the products of phototherapy are excreted in the bile 1.
- In cases of mixed hyperbilirubinemia, phototherapy may help reduce the indirect component but will not address the direct fraction.
- Diagnostic evaluation is essential when direct bilirubin levels are elevated, particularly in neonates, to identify underlying causes such as biliary obstruction, hepatocellular damage, or genetic disorders 1.
Clinical Implications
- Phototherapy should not be relied upon as the sole treatment for direct hyperbilirubinemia, and underlying causes should be identified and treated directly 1.
- In infants with cholestatic jaundice, phototherapy may cause a dark, grayish-brown discoloration of the skin, serum, and urine, known as the bronze infant syndrome 1.
- Rare but serious complications, such as purpura and bullous eruptions, can occur in infants with severe cholestatic jaundice receiving phototherapy, and congenital porphyria or a family history of porphyria is an absolute contraindication to its use 1.
From the Research
Phototherapy Effect on Direct Bilirubin
- The provided studies do not directly address the effect of phototherapy on direct bilirubin, as they primarily focus on indirect hyperbilirubinemia and the use of phototherapy in treating neonatal jaundice 2, 3, 4, 5, 6.
- Phototherapy is commonly used to treat indirect hyperbilirubinemia, and its effectiveness in reducing total serum bilirubin levels is well-documented 2, 3, 4, 5, 6.
- However, the studies do not provide information on the specific effect of phototherapy on direct bilirubin levels, making it difficult to determine its efficacy in this regard.
- Some studies suggest that phototherapy may have adverse effects, such as hemolysis, allergic diseases, DNA damage, or even cancer, but these findings are not directly related to the effect of phototherapy on direct bilirubin 5.
- The use of ursodeoxycholic acid as an adjuvant treatment to phototherapy has been shown to decrease total bilirubin levels faster and shorten phototherapy duration, but its effect on direct bilirubin is not specified 4, 6.
Limitations of Current Research
- The current research primarily focuses on indirect hyperbilirubinemia, and there is a lack of studies specifically addressing the effect of phototherapy on direct bilirubin.
- Further research is needed to determine the efficacy and safety of phototherapy in treating direct hyperbilirubinemia and to explore its potential effects on direct bilirubin levels 5, 6.