Wiktionary
androstanedione
n. (context biochemistry English) Either of two isomeric steroids: 5α-androstanedione and 5β-androstanedione. In humans, 5α-androstanedione is a metabolic precursor of testosterone and estrone.
Wikipedia
Androstanedione
Androstanediones are a pair of isomeric steroids which differ at the 5-position. They are distinguished as 5α-androstanedione and 5β-androstanedione. In humans, 5α-androstanedione is a metabolic precursor of both testosterone and estrone.