Hormone profiles after intramuscular injection of testosterone enanthate in patients with hypogonadism.

To examine hormone levels after androgen replacement therapy (ART) in Japanese male patients with hypogonadism, nine Japanese male patients with hypogonadism (serum total testosterone (tT) or free testosterone (fT) levels of < or = 2.7 ng/mL or < or = 10 pg/mL, respectively; average age, 59 years) were enrolled. They were treated with 125 mg of testosterone enanthate by single intramuscular injection. Blood samples were collected on the morning of the day of treatment, pre-ART, as well as on days 1 to 7 and day 14 after administration. Serum levels of tT, fT, estradiol (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), and sex hormone-binding globulin (SHBG) were determined. On day 1 after administration, the mean serum levels of tT and fT were 7.62 ng/mL and 23.22 pg/mL, respectively. Serum levels of tT and fT on day 14 after administration were lower than their pre-ART values. One patient exhibited abnormally high serum tT and fT levels of 19.6 ng/mL and 44.4 pg/mL, respectively. Serum levels of LH and FSH began to decrease gradually on day 5 after administration. Serum levels of SHBG did not change throughout the observation period. Serum levels of E2 increased 1.7 times on day 1 after administration but returned to its pre-ART value by day 14 after administration. The dose of testosterone enanthate for male patients with hypogonadism requiring ART should be determined carefully because some patients exhibited high serum levels of androgen beyond the physiological range and gonadotropin was suppressed in all treated patients.