Carnitine status at birth of newborn infants of varying gestation.

This study assessed and compared the plasma and red blood cell concentrations of carnitine in cord blood samples from preterm (less than or equal to 36 wk, n = 53) and term (greater than or equal to 37 wk, n = 72) neonates. The mean (+/- S.E.) plasma carnitine concentration (PL[C]) was significantly higher in preterm than in term neonates (29.0 +/- 1.8 versus 22.4 +/- 0.8 nmole/ml; P less than 0.001). Likewise, the mean (+/- S.E.) red blood cell carnitine concentration (RBC[C]) was significantly higher in preterm than in term neonates (0.24 +/- 0.02 versus 0.14 +/- 0.01 nmole/mg Hgb; P less than 0.001). Both PL[C] and RBC[C] were particularly elevated in extremely immature neonates (less than or equal to 33 wk gestation). Linear regression analysis showed a significantly negative correlation between PL[C] and gestational age (r = -0.332; P less than 0.001), and between RBC[C] and gestational age (r = -0.531; P less than 0.001). Approximately 72.2 +/- 1.1% (mean +/- S.E.) of carnitine in blood was estimated to be contained in the RBC, and 27.8 +/- 1.1% (mean +/- S.E.) of carnitine was estimated to be in the plasma.