Δ⁴-Androstenedione (abbreviated as Δ⁴-dione), commonly referred to simply as androstenedione, and also known as androst-4-ene-3,17-dione or 17-ketotestosterone, is an endogenous androgen steroid hormone and intermediate in the biosynthesis of testosterone from dehydroepiandrosterone (DHEA). In turn, Δ⁴-dione is also a precursor of dihydrotestosterone (DHT), estrogens such as estradiol and estrone, and the neurosteroid 3α-androstanediol.