REGULATION OF GONADOTROPIN SECRETION IN TURNERʼS SYNDROME

To determine the role of body fat in regulating secretion of luteinizing hormone and follicle-stimulating hormone, the authors measured both at 20 minute intervals for 24 hours in 8 children with Turnerʼs syndrome.All 8 patients were short and had no pubertal signs. The range of chronologic age was from 127/12 to 158/12 years. Five of the patients were XO, and 3 were mosaics (2 were XX/XO and one was XX/XXr). No patient had any clinical evidence of an estrogen effect. The 24 hour mean luteinizing hormone concentration varied between 20.2 and 70.5 mIU/ml.; the mean ± S.D. for the 8 patients was 46.3 ± 16.1. The 24 hour mean follicle-stimulating hormone concentration varied between 60.4 and 229 mIU/ml.; the mean ± S.D. for the 8 patients was 146.2 ± 50.9.There was a significant negative correlation between body weight (r = −0.85; P < 0.01), lean body weight (r = −0.75; P < 0.05), surface area (r = −0.83; P < 0.05), body fat (r = −0.88; P < 0.01), percentage body fat (r = −0.84; P < 0.01) and the 24 hour mean luteinizing hormone concentration. There was a significant negative correlation between total body fat (r = −0.77; P < 0.05), percentage of body fat (r = −0.75; P < 0.05) and the 24 hour mean follicle-stimulating hormone concentration.The plasma estradiol concentration was measurable in only 2 patients. With use of the lowest detectable level in the 6 patients whose levels were below the limits of assay sensitivity, the mean ± S.D. plasma estradiol was 13.8 ± 5.6 pg./ml. The mean plasma estrone was 49.5 ±19.1 pg./ml. The 24 hour mean ± S.D. plasma androstenedione, testosterone and dehydroepiandrosterone sulfate were 0.39 ± 0.28, 0.10 ± 0.06 and 1053.8 ± 679.1 ng./ml., respectively. There were no significant correlations between the above estrogens and androgens and the 24 hour mean luteinizing hormone or follicle-stimulating hormone concentrations. In addition, there were no significant correlations between these 24 hour mean estrogen and androgen concentrations and the calculated values for body weight, lean body weight, body fat, percentage of body fat or surface area.In 2 patients with Turnerʼs syndrome (XO and XO/XX), the measured values of total body water were 26.2 and 13.2 liters, and the calculated values with the equation of Mellits and Cheek were 26.4 and 13.4 liters, respectively.