Benign Prostatic Hyperplasia (BPH)
Prostate Function and Causes of BPH
The main function of the prostate is to facilitate male fertility. This is accomplished through the liquid volume of ejaculate, rich in fructose, which functions as a fuel source for sperm, and also contains a protein called prostate-specific antigen (PSA). PSA is believed to help liquefy the ejaculate and promote sperm motility (McNicholas 2008).
The development of BPH is a multifactorial process. As men age, prostate cell growth becomes less well controlled by cell signaling activity. Also, the cells in the prostate become less responsive to signals that induce apoptosis or “programmed cell death”. This results in an overabundance of cells in the prostate, also known as prostate hyperplasia (McNicholas 2008).
This breakdown in cellular regulation that occurs with aging allows prostate cells to proliferate and promote the formation of additional tissue. This additional tissue is smooth muscle, and this tends to increase the overall muscle tone of the prostate, which can contribute to blockage of the urinary tract (McNicholas 2008).
Imbalanced hormone levels contribute to BPH. A derivative of testosterone called dihydrotestosterone (DHT) stimulates growth of the prostate. DHT is derived from testosterone via conversion by the enzyme 5α-reductase, which is an important pharmacologic target for BPH therapies (Lepor 2004). In addition, high levels of insulin-like growth factors and inflammatory markers (eg, C-reactive protein) can also contribute to BPH (Sarma 2012; McNicholas 2008).
Furthermore, ethnic differences have been reported, such as lower rates of BPH and prostate surgery among Asian men relative to Caucasian men. Furthermore, one study reported higher rates of moderate-to-severe lower urinary tract symptoms among Afro-Caribbean men relative to Caucasian men, whereas other studies have shown similar rates of BPH diagnosis and hospitalization among Afro-Caribbean men and Caucasian men (McNicholas 2008).