DHEAS (dehydroepiandrosterone sulphate) is a steroid hormone produced almost exclusively by the adrenal glands. It is the sulphated, storage form of DHEA and serves as a reservoir from which the body can produce other sex hormones including testosterone and oestrogen in peripheral tissues.

DHEAS levels peak in the mid-20s and decline steadily with age — by the age of 70, levels are typically 20–30% of their peak. This age-related decline has driven significant research interest in DHEAS as a marker of biological age and adrenal reserve. Clinically, it is used to investigate adrenal tumours, PCOS, premature adrenal insufficiency, and to assess the contribution of adrenal androgens to symptoms such as acne, hair loss, and low libido.