The Effect of 15-Hour Fat Infusions of Varying Dosage on Bilirubin Binding to Albumin

Abstract

Intravenous fat emulsions (1, 2, and 3 g/kg) were administered over 15 hr to 20 appropriate for gestational age premature infants with physiologic hyperbilirubinemia to determine the effect of fat infusions on the serum free fatty acid:albumin molar ratio (F/A) and on unbound bilirubin. Significant increases (p < 0.05) in F/A occurred with each increase in lipid dose in infants < 30 wk gestation, but not in infants ≥ 30 wk gestation. There was a direct linear correlation (r = 0.65, p < 0.001) between F/A ratio and unbound bilirubin (estimated fluorometrically by the ratio of albumin-bound bilirubin/reserve bilirubin binding capacity, B/R). The largest increases in unbound bilirubin (albumin-bound bilirubin/reserve bilirubin binding capacity) were seen in infants with F/ A > 4.0. The gestational age of infants with F/A > 4.0 was significantly less (p < 0.01) than infants with F/A < 4.0 (28.7 ± 0.47 us. 31.1 ± 0.40 wk, mean ± SEM). In 10/58 infusions there was a fall in unbound bilirubin, unrelated to birthweight, gestational age, postnatal age, however, during these infusions the end-infusion F/A was ≥ 3.0. We conclude that 1 g/kg of lipid emulsion infused over a 15-hr period has minimal risk of decreasing bilirubin binding in premature infants < 30 wk gestation. As doses of 2 or 3 g/kg are used, these infants may be at risk of decreased bilirubin binding, due to elevations in the F/A ratio. Monitoring of the F/A ratio may identify infants at risk for decreased bilirubin binding during lipid infusion and provide guidelines for determining the appropriate lipid dose. (Journal of Parenteral and Enteral Nutrition 9:144-147, 1985)