Androstenedione is an androgen, one of several "male" sex hormones that are responsible for the onset of sexual differentiation in males and females and the development of secondary male physical characteristics such as a deep voice and facial hair. Though it is considered to be a "male" sex hormone, it is present in the blood of both men and women and is a precursor that can be converted by the body into more potent androgens, such as testosterone, or converted into the female hormone estrogen. This test measures the amount of androstenedione in the blood.
Androstenedione is produced by the ovaries in women, the testicles in men, and by the adrenal glands in both. Adrenal gland secretion of androstenedione is stimulated by the pituitary hormone adrenocorticotropic hormone (ACTH).