High plasma vitamin C concentrations at birth associated with low antioxidant status and poor outcome in premature infants.

Concentrations of circulating antioxidants may be important in the aetiology of disease in premature infants. Blood samples were taken from 49 premature infants within two hours of birth. Plasma ascorbic acid, caeruloplasmin, and the ability of plasma to prevent lipid peroxidation in vitro were measured. Plasma ascorbic acid concentrations at birth ranged from 26.3 to 185.4 mumol/l. Plasma antioxidant activity at birth (microliter plasma required to inhibit lipid peroxidation) showed a strong negative correlation with plasma ascorbic acid and the plasma ascorbic acid to caeruloplasmin ratio. After correcting for gestational age and birth weight, plasma antioxidant activity at birth remained a significant predictor of mortality. Such plasma antioxidant activity is partly determined by the ferroxidase activity of caeruloplasmin. This may be modulated by high concentrations of ascorbic acid which may inhibit the antioxidant activity of plasma and thereby influence outcome.