Enlarged Prostate: Benign Prostatic Hyperplasia:
Benign prostatic hyperplasia (BPH), also called benign enlargement of the prostate, is a benign increase in size of the prostate.
The cause behind BPH is unclear, but two factors are necessary. The first is aging and the second is the presence of dihydrotestosterone (DHT). The enlargement of the prostate, which may be extremely variable from man to another, can result in various symptoms of voiding dysfunction, either obstructive or irritative in nature.
The various symptoms associated with voiding dysfunction, include a sensation of incomplete emptying, frequency, intermittency, urgency, weak stream, straining, post void dribbling and getting up to go at night. These symptoms are not necessarily related to the size of the prostate. In fact, some men with very large prostates have only mild symptoms of voiding dysfunction, and some with a small gland can be extremely symptomatic. So acute urinary obstruction that leads to urinary retention may occur in men independent of the size of the enlargement. In some men, acute retention may be precipitated by cough and cold medications, alcohol, excessive fluids, constipation, immobilization, anesthesia or a urinary tract infection.
Pathophysiology of BPH
BPH involves hyperplasia of the stromal and epithelial cells of the prostate. This growth results in the formation of large, fairly discrete nodules in the transition zone of the prostate. When sufficiently large, the nodules obstruct the urethra and increase resistance to flow of urine from the bladder. Obstruction of the urethra requires the bladder to contract harder during voiding. Just like your biceps enlarge with weightlifting the bladder muscle thickens and becomes more stiff, leading to progressive hypertrophy, instability, and decreased compliance of the bladder. PSA (prostate specific antigen) levels may be elevated in these patients because of increased organ volume and inflammation but BPH does not lead to cancer or increase the risk of cancer.
Prostate growth is believed to begin at approximately age 30 years. An estimated 50% of men have microscopic evidence of BPH by age 50 years and 75% by age 80 years; in 40–50% of these men, BPH becomes clinically symptomatic.
Signs and symptoms:
Benign prostatic hyperplasia symptoms are classified as either storage or voiding problems.
BPH can be a progressive disease, especially if left untreated. Incomplete voiding results in stasis of old urine and bacteria in the bladder and increases the risk of urinary tract infection. Urinary bladder stones can also be formed from the crystallization of salts in the residual urine. Urinary retention, is another form of advanced BPH. Acute urinary retention is the inability to void, while in chronic urinary retention the residual urinary volume gradually increases, and the bladder overdistends. This can result in a hypotonic (weak) bladder. Some patients who suffer from chronic urinary retention, also called obstructive uropathy, may eventually progress to renal failure.
What causes BPH:
Dihydrotestosterone (DHT), a metabolite of testosterone, is a critical mediator of prostatic growth. DHT is synthesized in the prostate from circulating testosterone by the action of the enzyme 5α-reductase.
DHT binds to nuclear androgen receptors and signals the transcription of growth factors that are mitogenic to the epithelial and stromal prostatic cells. DHT is 10 times more potent than testosterone. The importance of DHT in causing nodular hyperplasia is supported by clinical observations in which an inhibitor of 5α-reductase such as finasteride is given to men with this condition. Therapy with a 5α-reductase inhibitor markedly reduces the DHT content of the prostate and, in turn, reduces prostate volume and BPH symptoms.
Screening and diagnostic procedures for BPH:
A patient's history and voiding symptoms are the most important method of diagnosing BPH.
Rectal examination (palpation of the prostate through the rectum) may reveal a markedly enlarged prostate.
Blood tests are performed to rule out prostatic malignancy: elevated prostate specific antigen (PSA), PSA density and PSA free percentage.
These combined measures, PSA levels, rectal examination and transrectal ultrasonography, can provide early detection for prostate cancer and and differentiate from BPH.
Ultrasound examination of the testicles, prostate, and kidneys is often performed, again to rule out malignancy and hydronephrosis, a sign of obstructive uropathy.
Cystoscopy, where a scope is passed through the urethra into the bladder can help identify prostatic obstruction.
Management of Prostate Enlargement:
Lifestyle alterations to address the symptoms of BPH include decreasing fluid intake before bedtime, moderating the consumption of alcohol and caffeine-containing products, and following a timed voiding schedule. Patients can also attempt to avoid products and medications that may exacerbate symptoms of BPH, including antihistamines, diuretics, and decongestants, opiates, and tricyclic antidepressants.
Medical Treatment for BPH:
The two main medications for management of BPH are alpha blockers and 5α-reductase inhibitors.
Alpha blockers are the most common choice for initial therapy. They include doxazosin, terazosin, alfuzosin, tamsulosin, and silodosin. All five are equally effective but have slightly different side effect profiles.
Alpha blockers relax smooth muscle in the prostate and the bladder neck, thus decreasing the blockage of urine flow. Common side effects of alpha blockers include orthostatic hypotension, (a head rush or dizzy spell when standing up or stretching), ejaculation changes, headaches, nasal congestion, weakness and erectile dysfunction.
The 5α-reductase inhibitors finasteride and dutasteride are another treatment option. These medications inhibit 5a-reductase, which in turn inhibits production of DHT, the hormone responsible for enlarging the prostate. Effects may take longer to appear than alpha blockers, but they persist for many years. When used together with alpha blockers, a reduction of BPH progression to acute urinary retention and surgery has been noted in patients with larger prostates. Side effects include decreased libido and ejaculatory or erectile dysfunction.
Overactive bladder meds may also be used, especially in combination with alpha blockers. They act by decreasing the spasticity of the smooth muscle of the bladder, thus helping control symptoms of an overactive bladder.
In 2011, the U.S. Food and Drug Administration approved tadalafil (Cialis) to treat the signs and symptoms of benign prostatic hyperplasia, and for the treatment of BPH and erectile dysfunction, when the conditions occur simultaneously.
Minimally Invasive Surgical Treatment for BPH:
If medical treatment fails, transurethral resection of prostate (TURP) surgery may need to be performed. This involves removing the obstructing portion of the prostate through the urethra. There are also a number of new methods for reducing the size of an enlarged prostate. These include various methods to destroy or remove part of the excess tissue while trying to avoid damaging what's left. Transurethral electrovaporization of the prostate (TVP), laser TURP, visual laser ablation (VLAP), Greenlight and Bipolar TURP and others are in use.
Conventional (monopolar) TURP, electrical current passes through the patient from the active electrode (connected to the resectoscope loop) to a grounding pad attached to the patient; this has potential risks, such as skin burns, excessive heating of deep tissues, nerve damage, inadvertent nerve stimulation (e.g. obturator reflex) and cardiac pacemaker malfunction. Additionally, conventional TURP requires nonhemolytic, hypo-osmolar irrigation fluids (e.g. glycine), which, if absorbed in high volumes, may lead to TUR syndrome. In an attempt to address some of these disadvantages, bipolar technology was proposed as an alternative treatment for BPH.
One of the newest, widely used technologies and safest is the Bipolar Transurethral Vaporization (TUVP). Bipolar works by running electricity between an active and a passive electrode, which results in a vapor (plasma) layer at the interface of the prostate tissue. The high energy contained within this plasma layer is released locally into the tissue on contact, and causes tissue vaporization. Normal saline is usually used as an irrigant, which should help eliminate the risk of TUR syndrome. Additionally, the risk of thermal injury to surrounding tissue is minimized, and there is also decreased risk of skin burns and interference with cardiac pacemakers.