I am going to answer the sample USMLE Step 1 Questions with Explanation. These questions are available at USMLE.org
Q- A 62-year-old man comes to the physician because of a 6-month history of urinary hesitancy and dribbling after urination. He has to urinate two to three times nightly. Physical examination shows a diffusely enlarged, firm, and nontender prostate. Which of the following is most likely to have contributed to the development of this patient’s condition?
(A) Activation of the α1-adrenergic receptor
(B) Conversion of testosterone to dihydrotestosterone
(C) Conversion of testosterone to estradiol
(D) Inhibition of the α1-adrenergic receptor
(E) Production of prostate-specific antigen
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Answer
This patient has symptoms of benign prostatic hyperplasia (BPH), including urinary hesitancy, post-void dribbling, and nocturia. These symptoms are linked to an enlarged prostate, as noted on physical examination. The primary factor driving the development of BPH is the conversion of testosterone to dihydrotestosterone (DHT) by the enzyme 5α-reductase in prostate stromal cells. DHT binds to androgen receptors in the prostate, promoting cellular proliferation and growth of the prostate tissue, leading to the urinary symptoms described. Treatment of this condition includes finasteride which reduces the conversion of testosterone to DHT by inhibiting the 5α-reductase enzyme.
The correct answer is B
You are very welcome Dr. Izzat.
Thanks for sending me the mcqs