Unbound Bilirubin Levels in Phototherapy-treated Preterm Infants Receiving Soy-based Lipid Emulsion.

BACKGROUND Phototherapy is an effective treatment neonatal jaundice. Treatment indication uses total serum bilirubin (TSB), although unbound bilirubin (Bf) more accurately predicts handicap risk. The goals of this investigation were to examine the response of Bf and TSB to phototherapy in preterm infants, and we hypothesized that 1) TSB and Bf respond differently 2) the relationship between TSB and Bf is altered and 3) unexpected Bf elevations are found. METHODS Preterm infants below 2 kg at birth and receiving Intralipid (IL) were enrolled 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 TSB and Bf levels (41.4±6.9 hours) were 8.0±9.0 mg/dl and 16.9±12.4 nM (p 11 nM in 64, >17 nM in 18, and >22 nM in 7 infants. CONCLUSIONS Bf land TSB responded differently. While TSB and Bf correlated well before phototherapy, they did not 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.