STIMULATION TESTS OF PITUITARY‐LEYDIG CELL FUNCTION IN NORMAL MALE SUBJECTS AND HYPOGONADAL MEN

Abstract

SUMMARY The Leydig cell reserve was assessed by measuring plasma 17 ß‐hydroxy androgens (17 OHA) after two injections of human chorionic gonadotrophin (HCG) 2000 i.u. 3 days apart. In fifteen normal men the 17 OHA rose by a mean of 109%, to above 11 ng/ml, between 1 and 3 days after intramuscular injection. In cryptorchid boys the response was much slower, adult levels being reached in 1‐4 weeks. In panhypopituitarism 17 OHA levels rose rapidly to the normal range, whereas in isolated gonadotrophin deficiency the response was much more variable. Subjects with chromatin‐positive Klinefelter's syndrome also responded to HCG. No response was seen in patients with complete testicular degeneration. Peak serum HCG levels occurred at 24 hr. Pituitary luteinizing hormone (LH) production was tested with clomiphene citrate 3 mg/kg/day for 10 days. In nine normal men LH levels rose by a mean of 107% to above the normal range, and the 17 OHA by a mean of 114% to above 11.5 ng/ml. No response was seen in early puberty, in panhypopituitarism or in isolated gonadotrophin deficiency where LH and 17 OHA levels remained low. In Klinefelter's syndrome and testicular degeneration the high LH levels were unchanged. The HCG test is of value in confirming the presence of functioning Leydig cells, while the principal use of the clomiphene test is in diagnosing gonadotrophin deficiency, where basal LH levels may be only borderline low.