What causes benign prostatic hyperplasia (BPH)?
Benign prostatic hyperplasia (BPH) is probably a normal part of the aging process in men, caused by changes in hormone balance and cell-growth factors. Genetics may also play a role. This is especially true for severe BPH requiring surgery in
men younger than 60.
Men who have had their testicles removed do not develop BPH and, after castration, BPH has been observed to regress. In other words, the presence of normally functioning testicles appears to be necessary for the development of BPH. Abnormally growing prostate tissue may use male hormones differently than normal prostate tissue. Although this tissue growth is non-cancerous, as the tumor grows larger it can obstruct the urethra and interfere with the normal flow of urine. Men who are older than 50 have a higher risk of developing BPH. However, why some men have more severe symptoms than others is unknown.
A number of theories have been proposed to explain benign cell growth in older men.
Male Hormones - Androgens (male hormones) most likely play a role in prostate growth. The most important androgen is testosterone, which is produced throughout a man's lifetime. The prostate converts testosterone to a more powerful androgen, dihydrotestosterone (DHT). DHT stimulates cell growth in the tissue that lines the prostate gland (the glandular epithelium) and is the major cause of the rapid prostate enlargement that occurs between puberty and young adulthood. DHT is a prime suspect in prostate enlargement in later adulthood.
Estrogen - Some authorities believe that the female hormone estrogen may also play a role in BPH; some estrogen is always present in men. As men age, testosterone levels drop and the proportion of estrogen increases, possibly triggering prostate growth.
Late Activation of Cell Growth - Another theory focuses on cells in a certain section of the gland that may become active late in life, signaling other prostate cells to replicate or causing them to be sensitive to growth-stimulating hormones.
Defective Cell Death - This theory suggests that a process known as apoptosis, in which cells naturally self-destruct, goes awry and results in cell proliferation.
Blood Vessel Injury - Some experts theorize that the blood vessels in the prostate gland may deteriorate as men age, causing abnormal blood flow and oxygen loss, which would stimulate cell growth. Such a theory is supported by the presence of heart and circulatory problems in many men with BPH.