Growth hormone response to clonidine in anovulatory infertile women resistant to clomiphene citrate stimulation

Objective: To evaluate the GH response to the clonidine test in a group of infertile women and to determine their ovulatory response to clomiphene citrate (CC) stimulation. Design: Prospective study. Setting: Reproductive endocrinology unit. Patient(s): Thirty-three anovulatory infertile women (age range, 25–36 years) and 9 healthy controls with normal ovulation. Intervention(s): In the early follicular phase, 0.3 mg of clonidine was administered between 8:30 and 9:00 a.m. and blood samples were collected for 120 minutes thereafter for measurement of serum GH levels. Plasma levels of insulin and glucose were measured after a 75-g glucose load, and CC was given at a dosage of 50–250 mg/d for ovulation induction. Main Outcome Measure(s): Serum concentrations of GH, insulin-like growth factor I, insulin, and insulin-like growth factor binding protein-1. Result(s): On the basis of their ovulatory response to CC, 15 patients were considered nonresponsive (group 1) and 18 patients were considered responsive (group 2). Baseline levels of GH, insulin-like growth factor I, and insulin-like growth factor binding protein-1 were similar in the two groups of patients and the controls. The GH response to clonidine was significantly greater in group 2 and in the controls than in group 1. Concentrations of insulin and glucose after the glucose load were not different among the three groups. Conclusion(s): Women who were resistant to CC had a reduced GH response to clonidine. These data suggest that adequate GH secretory capacity is important for CC action.