Studies on pituitary-gonadal endocrine function in XYY men.

Serum luteinizing and follicle-stimulating hormones and testosterone levels were studied in 11 patients with 47-XYY chromosomes and a comparison was made to normal men and patients with other testicular diseases, including Klinefelter's syndrome. Serum follicle-stimulating hormone levels in patients with XYY chromosomes were elevated significantly in comparison to those in normal men but lower than those in men with Sertoli cell only syndrome and Klinefelter's syndromes. Serum luteinizing hormone levels were somewhat elevated and serum testosterone levels were somewhat low in comparison to normal men, although the difference was not significant. Results of the short-term human chorionic gonadotropin stimulation test suggested almost normal Leydig cell reserve capacity in patients with XYY chromosomes.