Benign Prostatic Hyperplasia
Benign Prostatic Hyperplasia
Benign Prostatic Hyperplasia od BPH – Hello. My name is Zach Goldsmith. I’m a resident in neurology at Duke. Today we’re going to be discussing a very common condition, benign prostatic hyperplasia, or BPH. We’re going to begin by discussing the important anatomy of this very common condition.
In addition, we’ll discuss the physiology of prostate growth and discuss how this relates to the abnormal growth, which contributes to lower urinary tract symptoms of Benign Prostatic Hyperplasia. Next we’ll be discussing an approach to evaluate male patients with lower urinary tract symptoms.
Finally, we’ll discuss the medical and surgical management of this condition. BPH is extremely common. The prostate grows with age. It’s estimated that half of 60-year-old men have prostatic enlargement. Therefore, it’s important to understand the essentials regarding the evaluation and management of Benign Prostatic Hyperplasia regardless of your chosen medical specialty. The prostate is located deep within the male pelvis. It sits just past the outlet of the urinary bladder.
The urethra also originates in this area and travels through the prostate. So as you can see, during voiding, urine is essentially squeezed through the prostate. There are multiple zones of the prostate. The transitional zone is located within the prostate gland and actually surrounds the urethra. This is where Benign Prostatic Hyperplasia usually occurs. In contrast, the peripheral zone of the prostate, which is located towards the exterior of the gland is where most prostate cancers tend to originate.
And you can imagine that BPH of the transitional zone can essentially block off urine flow through the urethra. Whereas prostate cancers which originate in the peripheral zone can be palpated through a digital rectal examination. There are two primary signaling axes that regulate growth and function of the prostate– testosterone, as well as adrenergic innervation. Testosterone synthesis, which is shown on these two schematics, is synthesized primarily by the testicles, but also by the adrenal gland.
Its synthesis is regulated by pituitary signaling. Testosterone is converted to its active form, dihydrotestosterone or DHT, by an enzyme that is expressed within the prostate cells called 5-alpha reductase. DHT then stimulates transcriptional upregulation of many genes involved in prostate growth. 5-alpha reductase is an important drug targeted for BPH. Adrenergic signaling from the sympathetic nervous system also is important to understand prostate function.
Alpha-adrenergic receptors, when stimulated, result in smooth muscle contraction within the prostate, urethra, and bladder neck. Alpha-adrenergic receptors are another important drug target for BPH. So recalling the anatomy of the prostate gland, you can imagine how its growth can lead to obstructive urinary symptoms. Many of the symptoms of BPH, including straining, as well as urinating hesitancy– which is difficulty initiating a urinary stream.
Both of these can be related to obstruction at the level of the bladder neck. In addition, incontinence, which is involuntary leakage of urine and nocturia, which is waking at night to empty your bladder, are also related to bladder outlet obstruction. So when evaluating a male patient with lower urinary tract symptoms that are suspicious of BPH, it’s important to start with a targeted medical history. How many times per night do you wake up to empty your bladder? Are you having trouble initiating your stream? These are the questions that you want to be asking. In addition, it’s important to assess the degree of bother for each individual patient.
The digital rectal examination is important both to assess the size of the prostate, as well as to seek out hard nodules that would be suggestive of prostate cancer. Urine testing is also important to rule out infections which can cause similar symptoms as BPH. A uroflow test is a noninvasive test that can be done to determine if there’s a decreased force of stream which can also suggest bladder outlet obstruction.
The International Prostate Symptom Score, or IPSS, is a validated scale that can be used to quantify the severity of each patient’s symptoms. This can also be used to quantify symptoms over time and, for example, to see how patients are responding to medical treatment. So there are very effective medical treatments for Benign Prostatic Hyperplasia, but before starting medication, it’s very important to assess if the patient has any modifiable behavioral factors that can be adjusted that can exacerbate the symptoms of BPH.
For example, diuretics, caffeine intake, as well as fluid intake, particularly in the evening, all of which can exacerbate the symptoms of BPH. There are two main classes of medications. 5-alpha reductase inhibitors, which block the conversion of testosterone to dehydrotestosterone.
These actually decrease the size of the prostate, but they take a longer time to work. Their onset is weeks to months time. In addition, there are some sexual side effects, such as decreased libido, which have been associated to some men taking 5-alpha reductase inhibitors. On the other hand, alpha blockers decrease the adrenergic tone to the prostate and bladder neck.
They work faster than the 5-alpha reductase inhibitors, but they do not actually shrink the size of the prostate. Side effects include dizziness and orthostatic hypotension, both of which are rare with these medications. Common indications for surgery include men who have failed medical therapy. Or patients who are in urinary retention, who are completely unable to void and require a catheter. These patients are also very good surgical candidates.
Finally, men with recurrent urinary tract infections or bleeding from prostatic enlargement are also common indications for surgery. Most surgeries are performed endoscopically through the urethra. Prostate tissue may be excised or coagulated using electricity or lasers. Some men with very large prostates may be better suited for an open operation. So to review, BPH occurs primarily in which zone of the prostate? The transitional zone.
Prostate cancer occurs in which zone of the prostate? The peripheral zone. Three components for an evaluation of a male with lower urinary tract symptoms include digital rectal examination, International Prostate Symptom Score, and a urinalysis. Which class of medications for BPH work the fastest? Alpha blockers. Which class of medication actually decreases the size of the prostate? 5-alpha reductase inhibitors. Here are some additional reference materials. And thanks very much.
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