Melatonin secretion in Turner's syndrome: lack of effect of oestrogen administration

Melatonin secretion was investigated in 13 girls with Turner's syndrome before and after long-term oestrogen administration. Oestrogen treatment resulted in an increase in the serum levels of the hormone and a decrease in blood progesterone concentration. No change, however, was observed in the melatonin secretion pattern (in terms of peak values, time of peak level and total melatonin secretion) after oestrogen therapy. A distinct circadian rhythm in serum melatonin was evident in all subjects with peak occurring around 0200 h and concentration similar to those of normal subjects.