WHY DOES THE PROSTATE CAUSE URINARY SYMPTOMS?
In a recent post we became acquainted with this feisty gland. We discussed the fact that the prostate grows throughout a man’s life. We also discussed the fact that the prostate surrounds the first portion of the urethra. As the prostate grows, men may experience symptoms such as urinary frequency and urgency. But why is that?
Well, as the prostate grows outward it also grows inward, putting pressure on the urethra, thus obstructing the flow of urine out of the bladder. This can make it harder for the bladder to empty. Failure to empty causes frequency of urination because it doesn’t take long for the bladder to become full again. But failure to empty is really a small part of the problem.
Much of the problem is related to what is called “failure to store.” What does this mean? Well, the bladder’s job is to store urine, hopefully at least 10 ounces or so, before sending a signal to the brain saying “I have to pee.” Because most peoples’ kidneys make about 70 ounces of urine a day, the average number of daily trips to pee is about 7 (it’s math). The bladder is a relatively thin muscle that squeezes to expel urine when you pee. In order for the bladder to store that much urine, it must be stretchy or “compliant.” A compliant bladder accumulates urine without significant increase in pressure (stretches easily). It is able to stretch because it is thin.
So what happens when the prostatic urethra becomes narrower as the gland grows? The bladder has to squeeze harder to get urine out. It is basically doing resistance training. What do muscles do when they work out? They get thicker. An obstructed bladder becomes thick walled (AKA hypertrophy). Do you see where this is going yet? A thick-walled bladder no longer stretches easily (becomes less compliant). So it can no longer store as much urine before the pressure gets high enough to tell the brain it’s time to pee. It may store 5 or 6 ounces rather than 10. This causes urinary frequency. In addition, the bladder pressure goes up suddenly as the bladder fills due to reduced compliance. This causes urgency. So you see, what starts as a prostate problem becomes a bladder problem!
These symptoms can be treated by medicines that act on the prostate as well as medicines that act on the bladder. An experienced doctor will know which approach is more likely to work based upon several factors.
Taking testosterone supplementation can make the prostate grow. It is not actually the testosterone itself that causes growth, but rather the conversion of testosterone into dihydrotestosterone (DHT). DHT causes prostate growth and also causes male pattern baldness. Fun fact: that is why medicines such as finasteride, which works by blocking conversion of testosterone to DHT, are used to shrink the prostate and also to reverse hair loss. When finasteride first came out, it was marketed under two names—Proscar to treat enlarged prostate and Propecia to treat hair loss. Same drug, more money for Merck.
The relationship between testosterone and the prostate is one of the many reasons that urologists are best equipped to manage testosterone optimization treatment.