PLASMA RETINOL-BINDING PROTEIN RESPONSE TO VITAMIN-A ADMINISTRATION IN INFANTS SUSCEPTIBLE TO BRONCHOPULMONARY DYSPLASIA

We hypothesized that changes in plasma retinol-binding protein (RBP) concentration in response to vitamin A administration might be useful for evaluating vitamin A status of very low birth weight infants susceptible to bronchopulmonary dysplasia. We prospectively studied 24 consecutively admitted neonates (birth weight <1350 gm, gestational age<31 weeks, ventilator dependent for>24 hours after birth), who were eligible to receive 2000 IU suplemental vitamin A by inframuscular injection on postnatal day 1 and on alternate days thereafter for 28 days. In addition to serial assessment of vitamin A status, we measured plasma RBP just before and 1, 3, and 6 hours after an intramuscular injection of vitamin A (2000 IU/kg retinyl palmitate) on days 1 and 28. The percent incrase in plasma RBP (-RBP) was high (mean±SD: 61±37%) and plasma vitamin A and RBP values were low on day 1, indicative, of vitamin A deficiency. Supplemntal vitamin A improved vitamin A status of all infants as shown by low -RBP (mean±SD: 8±9%) and normal plasma vitamin A and RBP values on day 28. Bronchopulmonary dysplasia was diagnosed in 12 of 24 infants. Infants with bornchopulmonary dysplasia had a higher mean (±SD) -RBP on day 28 than those without bronchopulmonary dysplasia (13±10% vs 3±3%, p<0.01), indicative of persistence of low vitamin A status in infants with lung disease despite supplementation. We conclude that the plasma RBP response to vitamin A is a useful indicator of vitamin A status in very low birth weight infants. Although vitamine A supplmentation at the dosage used in this study normalizes conventional plasma indexes of vitamin A in very low birth weight infants, the plasma BRP reponse to vitamin A may continue to reflect persistence of low vitamin A status in the more immature infants with significant lung disease. We suggest that the plasma RBP response to vitamin A may be a useful functional test in such infants. © 1990 The C.V. Mosby Company.