In a series of 146 school girls and nurses in training, the serum levels of growth hormone (GH), follicle stimulating hormone (FSH), and luteinizing hormone (LH) were determined in the afternoon after 4–5 hours' fast. Blood specimens of the menstruating girls were taken on the 7th to 10th day from the beginning of the preceding menstrual bleeding. From the 24-hour urines collected on the previous day the excretion of total oestrogens, 17-ketosteroids and 17-hydrocorticosteroids was determined. The series was grouped according to skeletal age which varied from 8.0 years to the adult stage.
In the girls aged 11-13 years the GH curve showed a significant rise parallel with the mean height curve. The FSH values at the early age of 8–9 years corresponded to the follicular phase of adult women. The LH level increased steeply up to the 15th year of bone age and the mean values of adults were found to be about three times those of childhood. The excretion of total oestrogens and 17-ketosteroids increased steadily up to the full maturity of skeletal age. In the oldest group of girls the excretion was about four times that of the group aged 8–9 years. The hormonal maturation seems to continue until late puberty. The 17-OHCS, on the other hand, reached the adult level in the group with a bone age of 13 years. The excretion of 17-OHCS shows a steep rise from the age of 11 to 12 years and this acceleration of excretion perhaps exceeds the increase in surface area.