Abstract 213

Background: Electrospray tandem mass spectrometry is a powerful method for detection of inborn errors of fatty acid metabolism. The aim of this study was to investigate whether acylcarnitine concentrations in cord blood differ from postnatally drawn blood samples. Materials: Blood specimens of 69 healthy newborns (gestational age 37 to 42 wks, birth weight 2380 - 4420 gm) were taken from umbilical cord blood and spotted on a Guthrie card. A second sample of each infant was taken on the fifth postnatal day. Measurements: Small circles of dried blood were excised and extracted with methanol. The extracts were evaporated after addition of internal deuterated standards. The residue was butylated and analysed using a PE Sciex API 365 electrospray tandem mass spectrometer. Acylcarnitine concentrations were compared with the t-test for paired samples. Results: Concentrations of free carnitine were similar in cord blood and postnatally drawn samples. Compared to cord blood, the levels of acetyl- (p<0,001), propionyl- (p<0,05), isovaleryl- (p<0,05), octanoyl- (p<0,05), decanoyl- (p<0,05), lauroyl- (p<0,001), myristoyl- (p<0,001), palmitoyl- (p<0,001) and stearoylcamitine (p<0,001) were significantly higher on the fifth postnatal day. No correlations with gestational age, birth weight or umbilical arterial pH were found. Conclusions: Levels of various acylcarnitines increase during the first postnatal days. This result may have implications for the use of cord blood samples for neonatal screening.