STUDIES ON THE TESTICULAR HYPOPHYSEAL RELATIONSHIP

Report 1. Studies on Secretion of Pituitary Gonadotropins in Man

Abstract

Serum LH and FSH levels were measured in prepuberal and pubescent boys, normal adult men and patients with testicular disorders by double antibody radioimmunoassay.
Serum concentrations of LH and FSH were determined in specimens obtained sequentially at 20 minute intervals for six hour periods in two young healthy men, a castrated man, a eunuchoid and one subject with Klinefelter's syndrome. From 4-7 abrupt elevations occurred in the 2 young adult males and the castrated man, but fluctuations in LH and FSH levels were less marked in the eunuchoid and the patient with Klinefelter's syndrome.
Serum LH and FSH levels in normal children and adults classified according to age were also measured. Although both serum LH and FSH level increased after 9 years of age in normal boys, the rate of increase of serum LH level became greater from prepuberty to pubescence while FSH levels increased only gradually.
There was a small, but significant, rise in serum LH and FSH concentration in men from the third decade (LH 30.9±15.6 (SD) ng/ml; FSH 103.3±46.3 (SD) ng/ml) to the fourth decade (LH 53.2±42.0 ng/ml; FSH 142.3±75.8ng/ml). The mean levels of LH and FSH in men over the sixth decade (LH71.3±49.1ng/ml; FSH 368.8±299.4ng/ml) were significantly higher than the mean level during the 2nd and 3rd decades.
From a practical standpoint, serum gonadotropins were also measured in boys with cryptorchism, subjects with Klinefelter's syndrome and castrated men. Serum FSH levels in boys with cryptorchism were generally higher than in normal boys of comparable ages. Serum LH and FSH levels from castrated men or subjects with Klinefelter's syndrome were remarkably elevated (LH 110 to 660ng/ml; FSH 255 to 2750ng/ml).
100 μg of synthetic LH-RH was administered to 4 adult males, 8 aged males and 12 subjects with Klinefelter's syndrome. The maximum net increases of LH were 254.4, 335.2 and 635.8ng/ml and serum LH showed increases of 10.9, 4.6 and 5.0 times the basal level, respectively. The maximum net increases of serum FSH were 169.0, 485.0 and 803.3ng/ml. The serum FSH rose 2.6, 2.2 and 2.0 times the pretest level of each group, respectively. The maximum response of serum LH was observed within 90 minutes in all cases but one who was 79 yrs old.
It is generally agreed that clomiphene citrate stimulates the pituitary-Leydig cell axis in men by inducing LH and FSH release. But, one subject showed a significant decrease in LH and FSH during clomiphene administration (200mg daily for 3 days), and another case revealed stimulation in FSH and a decrease in LH during administration.
Responses of serum gonadotropins after insulin injection and influence of surgical stress on serum gonadotropins were also studied.