Androstenedione hormone. Molecular model of the structure of the human hormone Androstenedione. Atoms are represented as rods and are colour- coded: carbon (blue), hydrogen (gold), and oxygen (red). Androstenedione is a steroid that is produced in the adrenal glands of both sexes and is a precursor of all the sex hormones. It is sold as a supplement under the brand name Andro but is banned from many sporting events due to athletes abusing it in order to enhance their performances.