Plasma LH and FSH were measured before and after
LHRH administration in 10 patients with
Turner's syndrome, in 7 with
anorchia, in 2 castrates, in 18 with
Klinefelter's syndrome, and in 11 prepubertal subjects with unilateral cryptochidism used as a control group. Basal LH was elevated in 4 and basal FSH in 8 of 10 patients with
Turner's syndrome. Four patients with
anorchia showed elevations of LH while FSH had increased in all of them. The two castrates had normal or slightly increased basal LH and definite elevations of FSH. Prepubertal subjects with
Klinefelter's syndrome had normal plasma LH and FSH levels, but showed a marked elevation when they developed puberty. After
LHRH administration, mean LH increased by 297% and FSH by 81% in
Turner's syndrome, while in
anorchia LH increased 757% and FSH 104%. After
LHRH administration, patients with
unilateral cryptorchidism had an LH increment of 316% and a FSH increment of 164%. Patients with prepubertal
Klinefelter's syndrome showed elevations of 261% for LH and 221% for FSH after
LHRH treatment. Adolescent subjects with
Klinefelter's syndrome had an increment of 352% for LH and only 13% for FSH after
LHRH administration. We have concluded that patients without functioning gonads fail to suppress
gonadotropin secretion even before puberty while the gonads of the prepubertal
Klinefelter's syndrome are able to control LH and FSH release. After puberty, in spite of the hypersection of LH and FSH observed in all subjects with agonadism there is a large pituitary reserve of the
gonadotropins. We suggest that the relative inability of pubertal patients with
Klinefelter's syndrome to increase FSH after
LHRH treatment might be due to the presence of an abnormal compound secreted by the gonads.