The androstenedione test is a quantitative measurement of the serum level of this steroid hormone. Androstenedione is a weak androgenic hormone and a major precursor in the biosynthesis pathway of both testosterone (in the testes, ovaries, and adrenal glands) and estradiol (in the ovaries). It is co-produced by the adrenal cortex and the gonads (ovaries and testes), making it an important marker for assessing total androgen production and identifying the source of hyperandrogenism.