FETAL AND NEONATAL FACTORS INFLUENCING FREE CARNITINE

Abstract

Background: Free Carnitine (FC) is now measured routinely in new-borns in Indiana. Studies with small numbers have suggested that FC may be dependent on fetal and neonatal factors. Objective: Our objective was to compare FC levels with various fetal and neonatal factors. Our goal was to establish normative data by gestation in a very large cohort (Indiana State) and to use these carnitine values to develop hypotheses about FC in fetal life and disease. Design/Methods: Indiana State Health Department FC values (tandem mass spec) and demographic variables were obtained for the years 2005-2010. Gender, race, birth weight, gestation, NICU admission, age at collec-tion information was also evaluated. Multivariate fixed effect models were used to compare carnitine values with independent variables. Results: The number of newborns analyzed was 459,932. FC levels were lowest in babies with gestational age 37-40 weeks and higher in both preterm and post-term babies (Table 1). Table 1. Free Carnitine vs. Gestation Gestation FC mean SE mean Gestation FC mean SE mean 23 40.88 1.00 33 39.81 0.28 24 39.86 0.73 34 38.28 0.22 25 42.61 0.69 35 37.14 0.19 26 42.77 0.64 36 36.37 0.17 27 42.65 0.63 37 35.76 0.20 28 42.47 0.57 38 35.11 0.22 29 43.51 0.53 39 35.04 0.19 30 40.4 0.46 40 35.36 0.07 31 41.96 0.41 41 38.58 0.48 32 40.65 0.34 42 40.96 1.52 FC levels were lowest in babies with birth weights between 3150-4050g (34.390.07) and higher in groups with both lower (<2500g;39.540.08**, 2500-2850g;35.82 0.08**, 2850-3150g;34.890.08) and higher weights (>4500g;35.660.1**). FC levels were lowest when collected be-tween 24-48 hours (34.290.05) and higher either before (36.930.1**) or after that time (2-3,3-4,4-5,>5days;34.960.06**,36.210.11**,37.320.15**,36.80.14**). Female, white, non singleton and non NICU babies had significantly lower FC levels (Table 2). Table 2. Free Carnitine vs. Demographics Category FC mean SE mean Male 39.40 0.08 Female 36.60 0.08** White 37.16 0.06 Black 37.34 0.08* Asian 39.12 0.18** Other 38.39 0.1** Singleton 38.30 0.06 Multiple 37.70 0.11** NICU 40.46 0.09 Non-NICU 35.55 0.07** *&** are p<0.05 & <0.01 vs. comp group Conclusions: FC values are significantly influenced by gestation, gender, race, time of collection, NICU admission, multiple birth and birth weight. Generally, factors which increased mortality and morbidity (immaturity, post maturity, low birth weight, male gender, black race) were associated with higher FC values. These data will be used to construct normative curves and may be useful in predicting neonatal outcomes (Figure 1). 1Biostatistics, University of Cincinnati Medical Center, Cincinnati, Ohio, 45267