Twenty-four-hour growth hormone (GH) profiles in 26 girls with Turner's syndrome were compared with those of 26 normally growing short children and 24 slowly growing short children. All children were prepubertal and below 12 years of age. A subgroup of 13 girls was treated with ethinyl estradiol and a 24-h GH profile was reassessed. In an additional group of 45 girls with Turner's syndrome (aged 6.7-18.9 years) the effect of age, spontaneous breast development and ethinyl estradiol treatment was studied. The profiles were assessed by Fourier analysis. The oscillatory activity and the mean 24-h GH concentration were similar in children with Turner's syndrome and the normally growing short children, in contrast to lower levels in the slowly growing short children. The periodicity of GH secretion was similar in all groups. In the longitudinal study, ethinyl estradiol treatment resulted in a significant increase in pulse amplitude, but not in periodicity. In the cross-sectional study there was no significant difference between the subgroups of girls with either presence or absence of breast development or ethinyl estradiol treatment. GH secretion was not significantly related to age, height in standard deviation score or height velocity. These data imply that there is no abnormality in GH secretion in girls with Turner's syndrome
