ADRENOCORTICAL STEROID METABOLISM IN NEWBORN INFANTS. IV. PLASMA CONCENTRATIONS OF CORTISOL IN THE EARLY NEONATAL PERIOD*

Abstract

Determinations of material yielding the Porter-Silber reaction in extracts of umbilical cord plasma were compared with determinations of cortisol by isotope dilution. Cortisol values were also determined in pooled venous plasma from infants aged 3 to 96 hours. The presence of nonspecific background material and possibly of other reacting steroid material in the cord plasma resulted in a distinct difference between values obtained by the colorimetric and by the isotope dilution techniques. The pooled plasma cortisol values rose in comparison with the cord blood values during the third to the sixteenth hours of life, and subsequently fell. Except in cord plasma, no circulating a -ketolic neutral steroids other than cortisol could be demonstrated by paper chromatography during the newborn period.