Improved methods for isolating cortisol metabolites from neonatal urine.

Urine was collected from newborns, children, and adults who had received a tracer dose of [3H] cortisol. The free and different types of conjugated cortisol metabolites were separated by ion-exchange chromatography. A modified Amberlite XAD-2 procedure was used, which enabled quantitative extraction of the extremely polar cortisol metabolites from urine from newborns. Large differences between the ion-exchange chromatographic patterns for neonates and adults were observed. Urine from neonates was shown to contain quantitatively important amounts of an as-yet-unidentified conjugate that was absent from urine from adults. The effects of three different hydrolytic methods on the neonatal steroid conjugates were studied and it was found that the unknown conjugate in urine from the newborn could be hydrolyzed by solvolysis only.