Assessment of growth hormone (GH) axis in Turner's syndrome using 24-hour integrated concentrations of GH, insulin-like growth factor-I, plasma GH-binding activity, GH binding to IM9 cells, and GH response to pharmacological stimulation

The GH axis was studied in Turner's syndrome (TS) patients. Thirty-seven prepubertal TS patients and 42 normally growing girls (NGG; 5.5-16.3 yr old), of whom 13 were prepubertal, were studied by 24-h continuous blood withdrawal and provocative tests. The 24-h integrated concentrations of GH (IC-GH), FSH (IC-FSH), and insulin-like growth factor-I (IC-IGF-I) as well as the IC-IGF-I/IC-GH ratio were determined. An increase in IC-GH with age and progression of puberty was found in NGG, but not in TS. IC-GH in the NGG was significantly higher than that in age-matched TS patients. Estrogen replacement therapy normalized IC-GH levels in 6 TS patients in whom these levels were subnormal for age. A positive correlation between IC-GH and IC-FSH or IC-estradiol was found in NGG (r = 0.462; P less than 0.01), but not in TS patients. The IC-IGF-I/IC-GH ratio was significantly higher in the TS than in the NGG group. Serum GH-binding activity and serum GH binding to IM9 cells in the TS group did not differ from those i...