Male pubertal development and the role of androgen therapy.

In boys, the hormonal changes that accompany normal puberty are well defined, as are the physical signs of pubertal development and the kinetics of the growth spurt. Most androgens are derived from the testes, although adrenal androgens may also contribute; testosterone can also be aromatized to estrogen to exert important effects during puberty. Androgens, but especially their conversion to estrogens by aromatase, have a major role in the dramatic changes in linear growth, secondary sexual characteristics, and changes to bone, muscle and fat distribution that occur during puberty. Androgen therapy for delayed puberty should permit full normal pubertal development and thereby also address some of the associated psychosocial problems. Adolescent boys with conditions of permanent hypogonadism (hypogonadotropic or hypergonadotropic) or transient hypogonadotropic hypogonadism (constitutional delay of growth and puberty) can benefit from testosterone therapy. Long-term testosterone therapy should be given for hypothalamic or pituitary gonadotropin deficiency, or for primary hypogonadism such as for adolescents with Klinefelter syndrome, if endogenous testosterone levels drop or levels of luteinizing hormone rise. Intramuscular administration every few weeks is effective, but newer cutaneous forms, for example, gels or patches, also show promise in permitting adolescent males to reach adult body composition.