According to the NIH, the benign prostatic hyperplasia causes are not fully understood, but a hormonal influence has been theorized. Benign prostatic hyperplasia is thought to be a normal part of men’s aging process. The enlargement of the prostate is related to alterations in hormone balance that occur throughout men’s lives and cell-growth factors, while it is known that genetics are also important in the process. "The cause of benign prostatic hyperplasia is not well understood; however, it occurs mainly in older men. Benign prostatic hyperplasia does not develop in men whose testicles were removed before puberty. For this reason, some researchers believe factors related to aging and the testicles may cause benign prostatic hyperplasia," states in the NIH.

Testosterone is a male hormone produced during men’s lifetime, while men also produce small amount of the female hormone known as estrogen. With aging, the amounts of active testosterone decrease in the blood, leaving space for higher amounts of estrogen. Therefore, some of the studies relate the disease to the unbalance between estrogen and testosterone created, which results in higher activity of substances that promote prostate cell growth. In addition, a correlation between benign prostatic hyperplasia and dihydrotestosterone (DHT), a male hormone that plays a role in prostate development and growth, is also thought to exist. Men continue to produce DHT despite the drop in testosterone, and it accumulates in the prostate, encouraging the growth of prostate cells.