The prostate gland consists of glandular and stromal
elements. The stroma contains smooth muscle and connective tissue. BPH involves
an increase of all elements of the gland, but with a relatively greater
increase of prostatic stroma.
The prostate requires male hormones (testosterone and dihydrotestosterone)
to grow. These hormones do not cause BPH, but are necessary for it to develop.
Ageing and male hormones are the only proven risk factors for developing BPH.
Any man with a normal prostate and functioning testes will develop BPH if he lives long enough.
The testes produce 95% of testosterone found in the body. Testosterone is
converted to dihydrotestosterone in the prostate gland. The prostate gland is
much more sensitive to dihydrotestosterone than testosterone. An enzyme called
5-alpha reductase mediates this conversion of testosterone to its active form.
5-Alpha reductase is specific to the prostate gland (it is not found anywhere
else in the body) and can be manipulated medically (see treatment section).
Dihydrotestosterone causes the formation of growth factors within the
prostate gland, which in turn lead to an imbalance between cell growth and
programmed cell death (apotosis).
The net effect of all this is a slow progressive enlargement of the prostate
gland over time. While the majority of older men have clinically enlarged prostate glands,
this per se does not necessarily lead to symptoms or complications.
BPH can cause symptoms due to its effect on the prostate itself, or due to
its obstructive effect on the bladder outlet (see symptoms).
Cancer and the South African man
Are you at risk for prostate cancer?