Valores de normalidad de fenilalanina en recién nacidos según edad gestacional y tipo de alimentación

Resumen

INTRODUCTION This study aims to set several cutoff values of phenylalanine (Phe) by gestational age and type of feed given to newborns. MATERIAL AND METHODS A descriptive study of Phe values obtained in the neonatal screening of newborns was performed over a period of 3 years. Blood samples of all preterm infants (n = 7,129) born in the province of Alicante were collected. Term newborns in General Hospital of Alicante (n = 4,702) were used as control. The following variables were analyzed: days from birth to the blood sampling, gender, type of feeding, birth weight and gestational age. Phe concentration was performed by a fluorometric technique (Perkin Elmer). Relationships between variables were determined by the non-parametric Kruskal-Wallis test. To elucidate the individual impact of each variable on the Phe concentration, a multivariant correlation analysis was performed. RESULTS Phe concentration is higher in infants fed with parenteral and/or enteral nutrition (1.50 mg/dl) compared to those fed with formula (1.20 mg/dl), and those with human milk (1.10 mg/dl). The very preterm infants have higher concentrations of Phe (1.40 mg/dl) compared to term infants (1.00 mg/dl). In multivariant analysis, Phe levels do increase as prematurity, and also rise in parenteral and/or enteral nutrition only used in preterm and very preterm infants (p = 0.000). CONCLUSIONS Phe concentration is higher in infants fed with parenteral and/or enteral nutrition and in those with an early gestational age. Gender does not influence Phe levels. Although Phe levels vary slightly between the first week of life compared to older ages, difference is very small and has no importance in order to be considered in a newborn screening programme which must be done during the first week of life and also must include late blood samples.