Between 6 and 8 years of age, while cortisol concentrations and production rates remain constant, urinary excretion and circulating concentrations of DHA, DHAS, and other adrenal androgens increase progressively. These hormonal changes, which constitute the adrenarche, are accompanied by the appearance of axillary and pubic hair and a transient acceleration of linear growth and bone maturation. Increased adrenarchal concentrations of adrenal androgens may also contribute to the observed developmental decrease in concentration of SHBG and increase in bioavailable testosterone that occur in preadolescent boys. It is not known if extraadrenal factors, intraadrenal factors, or a combination of both are responsible for the occurrence of adrenarche. However, known hormones, such as ACTH, prolactin, gonadotropins, and estrogens, do not appear to cause the adrenarche. During adolescence, ACTH and cortisol concentrations remain constant, but concentrations of adrenal androgens continue to increase. The existence of a relationship between adrenarche and puberty has been suggested, partly because increased concentrations of adrenal androgens in undertreated congenital adrenal hyperplasia have been associated with cases of true precocious puberty in boys. However, there is evidence against a causal relationship, including the observation that children with treated primary adrenal insufficiency have been found to enter puberty normally. Adrenarche may cause a transient acceleration of growth and serve as a permissive factor in male puberty but does not appear to be necessary for the initiation of puberty.