BRAIN LACTATE IN PRETERM AND GROWTH-RETARDED NEONATES

Glucose is the predominant cerebral energy source under physiological conditions, although other substrates may support cerebral metabolism. The present study was undertaken to determine if lactate is present i n the immature human brain, and if so, whether or not concentrations o f lactate differ between small-for-gestational-age and appropriate-for -gestational-age infants. Thirty stable, healthy infants with normal b rains were investigated. As the only nutrient, all received milk enter ally prior to the investigation, which was carried out without sedatio n. Mean gestational age was 35 completed weeks (range 28-41 weeks) and mean birth weight was 2170 g (range 855-4100 g). Proton nuclear magne tic resonance spectra from the striatal region were obtained while the infants were sleeping quietly. Lactate was present in all 10 preterm small-for-gestational-age and 10 of 13 preterm appropriate-for-gestati onal-age infants, and the concentration was inversely related to postm enstrual age (p < 0.002). In addition, lactate increased with the degr ee of growth retardation (p < 0.01). At present the significance of la ctate is unclear. Lactate may be produced locally or in peripheral tis sues, and may support brain metabolism.