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Unbound bilirubin levels in phototherapy-treated preterm infants receiving soy-based lipid emulsion
Thomas Hegyi1, Alan Kleinfeld2, Andrew Huber2
1Department of Pediatrics, Robert Wood Johnson Medical School, Rutgers, The State University of NJ, New Brunswick, NJ, USA.
Insights
Unbound bilirubin (Bf) levels in preterm infants did not decrease with phototherapy, unlike total serum bilirubin (TSB). Bf levels remained elevated, indicating potential risks even after treatment for neonatal jaundice.
Area of Science:
- Neonatal medicine
- Bilirubin metabolism
- Phototherapy research
Background:
- Neonatal jaundice is common and treated with phototherapy.
- Total serum bilirubin (TSB) guides treatment, but unbound bilirubin (Bf) better predicts neurological risks.
- Preterm infants may respond differently to phototherapy.
Purpose of the Study:
- To investigate the response of Bf and TSB to phototherapy in preterm infants.
- To determine if TSB and Bf levels change differently during treatment.
- To assess the correlation between TSB and Bf before and during phototherapy.
Main Methods:
- Enrolled 117 preterm infants (<2 kg birth weight) undergoing phototherapy.
- Measured TSB using the diazo method.
- Measured Bf using a fluorescent Bf sensor.
Main Results:
- TSB levels showed a trend towards reduction with phototherapy (8.0 to 5.8 mg/dL).
- Bf levels did not significantly change with phototherapy (16.9 to 14.1 nmol/L).
- The correlation between TSB and Bf was lost during phototherapy.
Conclusions:
- Bf and TSB respond differently to phototherapy in preterm infants.
- Elevated Bf levels persisted in a significant proportion of infants post-phototherapy.
- Monitoring Bf may be crucial for anticipating treatment needs and risks in jaundiced preterm infants.
Background:
Phototherapy is an effective treatment for neonatal jaundice. Treatment indication uses total serum bilirubin (TSB), although unbound bilirubin (Bf) more accurately predicts disability risk. The goals of this investigation were to examine the response of Bf and TSB to phototherapy in preterm infants, and we hypothesized that (i) TSB and Bf respond differently; (ii) the relationship between TSB and Bf is altered; and (iii) unexpected Bf elevations are found.
Methods:
One hundred and seventeen preterm infants <2 kg at birth and receiving (IL) were enrolled; and measurements of TSB and Bf were obtained. TSB was measured by the diazo method and Bf with a fluorescent Bf sensor BL22P1B11-Rh.
Results:
Initial mean (± SD) TSB and Bf levels (41.4 ± 6.9 h) were 8.0 ± 9.0 mg/dL and 16.9 ± 12.4 nmol/L (P < 0.05). The rates of rise (ROR) were 0.21 ± 0.10 mg/dL/h for TSB and 0.38 ± 0.33 nmol/L/h for Bf. Phototherapy reduced TSB from 8.0 ± 9.0 to 5.8 ± 9.4 mg/dL (P = 0.068) but Bf did not change (16.9 ± 12.4 to 14.1 ± 9.4 nmol/L P = n.s.). Bf levels were >11 nmol/L in 64, >17 nmol/L in 18, and >22 nmol/L in 7 infants.
Conclusions:
Bf and TSB responded differently. While TSB and Bf correlated well before phototherapy, they did not correlate during phototherapy. TSB showed a trend toward a reduction with treatment, Bf did not. While TSB ROR information is not helpful, ROR Bf data can be utilized to anticipate treatment. Potentially high Bf levels existed before and after phototherapy and the mean Bf level at phototherapy termination remained elevated in a significant proportion of infants.
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