Lipid Emulsions and Unbound Bilirubin in Preterm Infants

Happy birthday Stan!

In previous work, it had been shown that free bilirubin (Bf) and unbound free fatty acids (FFAu) were increased in extremely low birth weight infants who received intralipid (soybean) at 3 g/kg/d.  A recent study (T Hegyi et al. J Pediatr 2017; 184: 45-50) showed that Bf and FFAu are increased with increasing intralipid dosage (1 to 3 g/kg/d) in all gestational ages (23-34 weeks).

The concern with Bf and FFAu is that elevated concentrations could have adverse neurologic effects; intralipids may act to displace bilirubin from binding to albumin. For most infants in this study, the levels “would not be expected to pose a neurotoxic risk” (per editorial pg 6-7).  Factors that enhance the generation of FFAu include infection, steroids, carnitine deficiency, and low albumin conditions. Phototherapy, in this study, reduced total serum bilirubin but not Bf in those receiving 2-3 g/kg/d of intralipid.

My take: This study does not provide any information regarding neurotoxicity.  It shows that potentially toxic levels of Bf & FFAu can occur in infants born <28 weeks who receive 2 g/k/day or more of intralipid.  While this is a concern, we also know that poor growth is associated with worsened neurocognitive outcomes (Nutrition Week: Downside of Lipid Reduction)

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