[Pituitary response to GnRH analogue testing in girls with a polycystic ovary syndrome]

THE AIM of our study was to estimate the gonadotropin level after GnRH analogue injection in girls with PCOS after suppression with dexamethasone.

57 girls with hirsutism, mean age 15.9 years, were involved in the study. The research was performed in the early and middle follicular stage. Menstrual disorders were observed in 78% of them. The patients were divided into 3 groups: I -- with clinical and laboratory symptoms of PCOS (menstruation disorders, testosterone >65 ng/ml and/or LH/FSH >2; n=29), II -- with menstruation disorders and without elevated androgen level (n=15), III -- without menstruation disorders and without elevated androgen level (n=13). Basal blood samples were drawn at 8 a.m. GnRH analogue (Relefact LH-RH) 100 microg was then given subcutaneously and blood samples were drawn every 4 hours for 24 hours.

Basal level of LH was the highest in group I (6,18+/-4,10 IU/l) in comparison with II (5.53+/-3.40 IU/l) and III (3.82+/-2.79 IU/l). After GnRH analogue administration mean LH concentration increased in all groups and peaked after 2 hours. Stimulated LH level was the highest in group I and differed statistically significantly from group III during the whole period of the test. The most significant difference occurred at 12 a.m. (p=0.003) and 10 a.m. (p=0.004). The FSH secretion in all tested groups was similar. It peaked, like LH, after 2 hours after GnRH analogue injection and decreased slightly during next 2 hours. A marked decrease was observed in the following period of time.

1. High and fast LH secretion responding to GnRH analogue indicates masculinization of the hypothalamo-pituitary axis in PCOS girls. 2. The hirsute girls without menstrual disturbances and hormonal abnormalities probably also have subtle masculinization of the pituitary response to stimulation by GnRH analogue.