PARATHYROID HORMONE-RELATED PROTEIN IN TRACHEAL ASPIRATES OF NEWBORN-INFANTS

PTH-related protein (PTHrP) is found with its receptor in a variety of normal mammalian embryonic tissues where it apparently regulates cell ular growth and differentiation. PTHrP stimulates phosphatidylcholine synthesis in rat fetal lung explants, suggesting a role in fetal type II alveolar maturation and surfactant production. We investigated PTHr P levels in tracheal aspirates of newborn infants. We collected trache al aspirates from 40 intubated newborn infants within the first 24 h o f life. PTHrP levels were measured by a RTA using rabbit antisera to P THrP peptide 38-64. We found significantly lower PTHrP levels in trach eal aspirates from infants born at less than 35 wk of gestation (p = 0 .02) and with a birth weight less than 2 kg (p = 0.04). We also found significantly lower PTHrP levels in male preterm (<35 wk of gestation) infants compared with female infants (p = 0.01), and in preterm infan ts who required multiple doses of surfactant (p = 0.005). Preterm infa nts exposed to antenatal steroids had significantly higher levels of P THrP in tracheal aspirates (p = 0.02). PTHrP is associated with variou s indices of lung maturation and may prove to be a mediator of differe ntiation and growth.