Plasma total corticosteroid concentrations were measured in 44 premature infants with the respiratory distress syndrome (RDS). Further assay of serum concentrations of cortisol, cortisone, corticosterone, corticosterone sulfate, and 11-deoxycorticosterone sufate was carried out in 24 of these infants and in 10 healthy, nonstressed premature controls. Infants with RDS had higher concentrations of cortisol (22.1±4.3µg/100 ml) and corticosterone sulfate (7.7 ± 0.8 µg/100 ml) than control infants (6.6 ± 0.8 µg/100 ml, 1.2 ± 0.3 µg/100 ml, and 4.2 ± 0.4 µg/100 ml, respectively).
A significant correlation was found with the five-minute Apgar score (negative correlation, p = 0.005) and a possible correlation with the A-aDO2 gradient. Among premature infants with RDS, those of 32 weeks' gestation or less had higher concentrations of cortisol (28.3 ± 23.6 µg/100 ml) and corticosterone (3.9 ± 2.7 µg/100 ml) than those of more than 32 weeks (11.5 ± 5.4 µg/100 ml and 1.7 ± 0.7 µg/100 ml, respectively), suggesting either elevated response to stress or a diminished ability to metabolize these compounds.