Ovarian sensitivity to follicle stimulating hormone is blunted in normo-ovulatory women with Down's syndrome.

Ovarian sensitivity to follicle stimulating hormone (FSH) during the early follicular phase of the human menstrual cycle was studied in six post-menarchal patients with Down's syndrome and 12 normo-ovulatory women. Pure FSH (75 IU) was given i.v. to six controls and six Down's syndrome patients, while saline was administered to the remaining six controls. Plasma concentrations of luteinizing hormone (LH), FSH, oestradiol, testosterone and growth hormone (GH) in samples collected for a period of 26 h after the injection were assayed. In control patients FSH injection increased oestradiol stimulated area under the curve (AUC). This value was significantly higher than that found in Down's syndrome patients (P < 0.02), who exhibited an oestradiol-stimulated AUC equivalent to saline-treated controls. In Down's syndrome, GH plasma concentrations were significantly lower than in the control group (P < 0.05). These results indicate that the ovarian sensitivity to FSH in patients with Down's syndrome is blunted. Lower GH plasma concentrations found in this group may in part account for this biological feature.