Hyperphenylalaninaemia in Parenterally Fed Newborn Babies

Phenylalanine Kinetics in Sick Preterm Neonates with Respiratory Distress Syndrome

“…Previously reported levels of amino acids in preterm infants receiving parenteral nutrition included a number with increased plasma phenylalanine concentrations (3)(4)(5)16). In contrast, Clark et al (17) found a low incidence of increased phenylalanine concentrations, with only one infant out of 109 very low birth weight babies receiving parenteral nutrition having a concentration greater than 600 pmol/L, although a number of infants were found to have increased tyrosine levels.…”

“…More recently, hyperphenylalaninemia has been described in sick preterm infants a s a complication of parenteral feeding with amino acid solutions. Although this is a transient phenomenon, levels have been reported in some infants in excess of 1000 p,mol/L (2)(3)(4)(5). The implications of these high phenylalanine concentrations 4XN, Wales, UK.…”

Metabolism of Intravenous Phenylalanine by Babies Born before 33 Weeks of Gestation

“…Sig nificantly raised plasma phenylalanine lev els, not invariably accompanied by raised plasma tyrosine levels, have been observed in a minority of sick babies receiving paren teral nutrition (PN) with regimens which had a high phenylalanine content [9][10][11]. Factors such as variable amino acid infusion rates, sepsis, and inadequate calorie supply probably contributed to the increase [12], but there was concern that sustained high phenylalanine levels might be neurotoxic.…”

Hyperphenylalaninaemia and outcome in intravenously fed preterm neonates.

“…Over the past five years there has been a number of reports of increased plasma phenylalanine concentrations in infants fed certain intravenous amino acid solutions, notably Vamin 9 (Kabi), which has been much used in Britain for term and preterm neonates. [1][2][3][4][5] As increased plasma phenylalanine in phenylketonuria is well known to be associated with long term neurological damage6 it has been argued, by analogy, that hyperphenylalaninaemia in intravenously fed infants could damage the developing brain.…”

“…A volume of 1 0 ,lI was then withdrawn and transferred to a round bottomed polystyrene tube, together with 92 [lI 0-2 M lithium citrate loading buffer (pH 2 2) containing the norleucine internal standard (250 nmol/ml) and the sulphosalicylic acid deproteiniser (2)(3)(4)(5) mg/100 [lI of 0-2 M lithium citrate. The sample was vortexed and allowed to stand at 4°C for one hour after which it was centrifuged at 2500 rpm for 15 minutes, also at 4°C.…”