Effect of intranasal LHRH therapy on plasma LH, FSH and testosterone, and relation to clinical results in prepubertal boys with cryptorchidism.

Synthetic LHRH (HOE 471) administered intranasally over a period of 4 weeks for treatment of uni- or bilateral cryptorchidism in nineteen otherwise healthy prepubertal boys led to increased basal and peak LH values and to markedly decreased peak FSH values in the i.v. LHRH test. Basal testosterone remained unchanged. Sixteen cryptorchid boys treated with placebo served as a control group. The reduced FSH response to i.v. LHRH could be due to induction of a gonadal feedback mechanism rather than pituitary depletion of FSH, in view of the favourable therapeutic effect and the increased LH secretion seen in some of our patients. Pretreatment LHRH tests were available in twenty successfully and in twenty-eight unsuccessfully treated boys. LH values were similar in both groups, whereas FSH peak values were significantly higher in boys who responded successfully to subsequent therapy. Testicular descent occurred most readily in boys with a large pool of easily releasable FSH and without a significant rise in testosterone (in contrast to HCG treatment). We suggest that FSH induces changes that potentiate the local action of testosterone.