| dc.description.abstract | Despite a number of published reports, there is limited infor-mation about carnitine metabolism in the newborn. To establish
normative data, we analyzed whole-blood carnitine concentra-tions in 24,644 newborns at age 1.85 0.95 d and umbilical cord
whole blood and plasma carnitine concentrations in 50 full-term
newborns. Total carnitine (TC), free carnitine (FC), and acylcar-nitine (AC) were measured by electrospray tandem mass spec-trometry. AC/FC ratios were derived from these measurements.
The entire cohort was stratified according to TC values into a
middle TC group representing 90% of the population and lower
and upper TC groups representing 5% of the population, respec-tively. Normative data were derived from the middle TC group of
full-term infants (N 19,595). TC was 72.42 20.75 M, FC
was 44.94 14.99 M, AC was 27.48 8.05 M, and AC/FC
ratio was 0.64 0.19 ( SD). These values differed significantly
from umbilical cord whole blood TC values of 31.27 10.54
M determined in 50 samples. No meaningful correlation was
found between TC and gestational age or birth weight in any
group. In controlled analyses, prematurity was not associated
with TC levels, whereas low birth weight ( 2500 g) and male
sex were significantly associated with higher TC levels. The
association of low birth weight with higher TC values may be
related to decreased tissue carnitine uptake. The sex effect may
be related to hormonal influences on carnitine metabolism. Our
study provides normative data of carnitine values measured by
the highly precise method of electrospray tandem mass spec-trometry in a large cohort of newborns and provides the basis for
future studies of carnitine metabolism in health and disease states
during the neonatal period. | es_ES |
