Age- and sex-related differences in urinary excretion of 6 beta-hydroxycortisol in humans.

A study of normal subjects showed that the 24-h urinary 6 beta-hydroxycortisol level is age-dependent, with a maximum at 14-20 yr in both men and women. The ratio of 6 beta-hydroxycortisol/cortisol also showed an age-dependent variation, being higher in children than adults. There was a significant difference between boys and girls aged 5-10 yr, but no difference in other subjects. No sex difference was demonstrable in the ratio of 6 beta-hydroxycortisol/cortisol. Examination of circadian rhythm revealed that 6 beta-hydroxycortisol and cortisol correlated well in children, but showed poor correlation in adults, with a lowered morning peak of 6 beta-hydroxycortisol.