Low-dose testosterone effect on somatic growth.

Low-dose testosterone has been found to preserve the growth potential of hypogonadal children requiring anabolic or androgenic therapy. Five girls with Turner syndrome were treated when their chronologic ages were 13 to 14 years and their bone ages were 10.6 to 12.75 years; six hypogonadal boys were treated when their chronologic ages were 11 to 15 years and their bone ages were 10.9 to 14.2 years. Depot testosterone was given as an anabolic agent in an average dose of 28 mg/m2/mo for 6 months to the patients with Turner syndrome and was given to initiate puberty in an average dose of 44 mg/m2/mo for 6 months to the hypogonadal boys. Growth rate doubled on these doses of testosterone, and bone age did not advance disproportionately. Consequently, height potential was preserved. Pubic hair advanced one Tanner stage during the 6-month treatment. Clitoral hypertrophy was observed in only one of the five girls with Turner syndrome and regressed when testosterone therapy was discontinued. Four hypogonadal boys were continued on low-dose testosterone until their bone ages passed 14 years of age and their growth rate waned. Then, the testosterone dosage was increased in increments to 100 to 200 mg/m2/mo. This group reached a height of 100.3 +/- 0.8% of the height initially predicted. In addition, all attained an adult height at least 15 percentiles greater than that before therapy. These studies indicate that testosterone in very low doses resembles "anabolic steroids" in that growth is stimulated without an inordinate androgenic effect. Furthermore, these studies show that institution of low-dose therapy in the early teenage years stimulates pubertal growth normally without loss of height potential.