Measurement of serum vitamin E isomers in fullterm and preterm infants.

BACKGROUND: This study was conducted with the following aims: (1) to construct a methodology by high-performance liquid chromatography (HPLC) to measure vitamin E levels in our neonatal units; (2) to establish a reference range of serum vitamin E levels in fullterm neonates and their mothers; and (3) to compare these to levels in the preterm group.
METHODS: During a 6-month period from September 1996 to February 1997, cord blood of 34 uneventful fullterm neonates (gestational age 38-42 weeks, birth weight 2840-3530 g) and venous blood of their healthy mothers were collected. Venous blood of 35 preterm neonates (gestational age 28-34 weeks, birth weight 940-1980 g) was collected at the same time. Serum vitamin E levels were measured by HPLC. The serum vitamin E/total lipids ratio was also examined.
RESULTS: Serum levels of alpha-tocopherol in 34 fullterm neonates and their mothers were 0.212+/-0.127 and 1.160+/-0.513 mg/dl, and of gamma-tocopherol were 0.029+/-0.019 and 0.214+/-0.122 mg/dl, respectively. All fullterm neonates except 2 had serum levels less than 0.5 mg/dl. There was a positive relationship between serum E levels and total lipids. In addition, the correlation between neonatal vitamin E/total lipids ratios and maternal vitamin E/total lipids ratio was statistically significant. The serum level of alpha-tocopherol in 35 preterm infants was 0.170+/-0.090 mg/dl and that of gamma-tocopherol was 0.020+/-0.015 mg/dl; both levels were much lower than those of their fullterm counterparts. But the vitamin E/total lipids ratios did not significantly differ.
CONCLUSIONS: We conclude that (1) measurement of serum vitamin E levels by the HPLC method is practical, and is useful in evaluating deficiencies in preterm infants and possibly useful in monitoring the adequacy after supplementation in future study, and (2) preterm infants had a much lower level of serum tocopherol, but no difference was seen in vitamin E/total lipids ratio.