72-year-old (male) with nocturia

by Mohammad Hajighasemi-Ossareh, MD, MBA

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    00:02 A 72 year old male of Asian descent visits your office frustrated regarding the frequency he wakes up at night to urinate.

    00:11 He comments that he is even avoiding to drinking fluids at night, but his symptoms have progressively worsened, Physical examination reveals an enlarged, symmetrical prostate free of nodules.

    00:23 If you wish to intervene in the main factor contributing to the pathogenesis of this patient's condition, which of the following should you prescribe? Answer choice (A) - Tamsulosin Answer choice (B) - Finasteride Answer choice (C) - Prazosin Answer choice (D) - Tadalafil and answer choice (E) - Leuprolide Now take a moment to come to the answer by yourself before we go through it together.

    00:51 Okay, let's jump right in.

    00:53 Let's discuss the question characteristics.

    00:55 Now this is a pathology question as the patient is having some kind of problem that's giving him nocturia and even though he decreases his fluid intake, he persistently has problems, and it's a system regarding his urinary and reproductive tract so it's reproductive pathology.

    01:12 Now this is a 2-step question because we have to first come up with a diagnosis and then determine which medication we wish to prescribe.

    01:19 And the stem is absolutely required because we need to know clinical history to determine diagnosis and then come up with our desire to treat or plan to treat in this case as well.

    01:29 Now let's walk through this question together.

    01:31 The first step is to determine the diagnosis.

    01:33 Now this patient's complaining of nocturia and the presence of what the physical exam shows as an enlarged prostate.

    01:40 Now nocturia is a common presenting symptom of patients that have benign prostatic hyperplasia or BPH.

    01:47 Now in this case, we don't hear any other associated symptoms, thus in the absence of other symptoms, the likely diagnosis here is BPH.

    01:56 Now for step 2, we need to determine which treatment option is appropriate for this patient and that's the key.

    02:04 You always have to think what they're prescribing for the patient.

    02:08 Now of all the answer choices, Finasteride is the most appropriate treatment as it is effective in reducing prostate size in BPH and is well tolerated in the elderly.

    02:19 The most common side effect that we know of is related to sexual dysfunction due to the medication's action of inhibiting the conversion from testosterone to dihydrotestosterone.

    02:32 Now let's refer to our image to better understand this pathway and determine how finasteride works.

    02:39 Now here we see that... this is all occuring in the prostate cell.

    02:43 The testosterone is converted to 5AR1 and 5AR2 and those together, go to DHT which is dihydrotestosterone.

    02:51 Now if you look, you see that finasteride actually prevents the conversion of 5AR2 to DHT and in doing so, you have less dihydrotestosterone circulating.

    03:03 Now normally, the dihydrotestosterone would bind to the receptor complex which will cause increased cell growth and then also cause cell death.

    03:13 Now that's how you can develop BPH.

    03:15 Now if you inhibit that pathway and you have less (DHT), you can have less BPH.

    03:20 Thus the correct answer in this case is answer choice (B) - finasteride.

    03:25 Now let's go to the other answer choices as they could've been treatment for BPH but not appropriate for this specific patient.

    03:33 Now, tamsulosin and prazosin are effective in reducing nocturia in BPH and they could've been proper answer choices but not for this patient because these medications have the side effects of orthostatic hypotension and syncope due to their related alpha-1 adrenergic antagonism mechanism of action and thus that would make these two medications unsuitable for an elderly patient.

    04:00 The risk being too high of orthostatic hypotension, and thus then falling.

    04:05 Now the answer choices, Tadalafil is a phosphodiesterase-5 inhibitor which is used to treat erectile dysfunction - not appropriate in this case.

    04:13 And Leuprolide is a GnRH receptor agonist that is used in the treatment of hormone responsive cancers such as prostate and breast.

    04:22 Now BPH even though it is a hyperplasia, it is not cancer, so also not indicated.

    04:29 Now let's review some high-yield facts regarding BPH.

    04:32 Now BPH is common in men after middle age.

    04:35 In fact, it presents in around half of men aged over 50.

    04:39 BPH generally presents clinically with urinary symptoms such as frequent or the urgent need to urinate, increased need to urinate at night or nocturia, difficulty initiating urination, a weak urinary stream or a stream that starts and stops and a notice of dribbling at the end of urination, and the sensation of the inability to completely empty the bladder.

    05:02 Now the treatment of BPH.

    05:04 The mainstay of drug tretment of BPH are alpha-1 adrenergic blockers and 5-alpha reductase inhibitors.

    05:10 Now alpha blockers such as tamsulosin and prazosin are effective but common side effects here include orthostatic hypotension and syncope which may limit their use particularly in elderly patients just like the one described in this question.

    05:24 Now 5-alpha reductase inhibitors such as finasteride and dutasteride are effective and well tolerated.

    05:31 The only side effect here that is important is decreased libido and ejaculatory or erectile dysfunction.

    05:38 Now if we look back at our pathway, finasteride inhibits the 5-alpha reducatase enzyme which converts testosterone to dihydrotestosterone.

    05:48 Now surgery for BPH is actually a possibility but is generally reserved for patients for whom have failed medical treatment with drug therapy

    About the Lecture

    The lecture 72-year-old (male) with nocturia by Mohammad Hajighasemi-Ossareh, MD, MBA is from the course Qbank Walkthrough USMLE Step 1 Tutorials.

    Author of lecture 72-year-old (male) with nocturia

     Mohammad Hajighasemi-Ossareh, MD, MBA

    Mohammad Hajighasemi-Ossareh, MD, MBA

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