Metabolism of Cortisol by the Human Newborn Infant1

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Abstract
14C-cortisol was administered to 2 newborn infants and 1 adult, and the pattern of urinary metabolites analyzed and compared. Sixty-three to 86% of the radioactivity extracted in the unconjugated fraction and 86 to 99% of that extracted in the glucuronide fraction were accounted for in terms of known steroids. In the case of the infants, 6β-hydroxycortisol4 represented 64% of the radioactivity extracted in the unconjugated fraction, while tetrahydrocortisone (67 and 73%), cortolone (10 and 13%) and 6β-hydroxycortisol (16 and 13%) were the sole significant components of the glucuronide fraction. A small amount of radioactivity was extracted in the steroid sulfate fraction, but there was no detectable incorporation of 14C into cortisol sulfate. Substantial additional amounts of radioactivity became extractable by either butanol extraction (18%) or amberlite XAD-2 chromatography (28%) of the urine. In the adult control the distribution of the radioactivity in the unconjugated, glucuronide and sulfate fractions represented 8.7, 84.4 and 2.1% of the total radioactivity excreted. The data are interpreted as providing further evidence of the existence of alternate pathways of cortisol metabolism postnatally. Such pathways are denned by a decreased formation of steroid glucuronide and the excretion of highly water soluble metabolites—the nature of which remains to be denned. The data do not support the view that the excretion of 6β-hydroxycortisol, or the formation of cortisol sulfate, are of sufficient quantitative significance to qualify as compensatory mechanisms for the decrease in steroid glucuronide excretion.

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