Dehydroepiandrosterone sulfate (DHEAS) is the major precursor of 17-ketosteroids. DHEAS is a metabolite of DHEA, the principal adrenal androgen. DHEAS is primarily synthesized in the adrenal gland, with a small amount secreted by the testes. DHEAS is a weak androgen and can be converted into more potent androgens (e.g., testosterone) as well as estrogens (e.g., estradiol). It is secreted in concert with cortisol, under the control of adrenocorticotropic hormone (ACTH) and prolactin. Excessive production causes masculinization in women and children. DHEAS has replaced measurement of urinary 17-ketosteroids in the estimation of adrenal androgen production.