A 70 year old man has severe urinary hesitancy associated with bPH. He has * tried alpha blockers with little effect. His physician recommends a drug that blocks 5α-reductase in the prostate which is:

Correct Answer: B

Rationale: The correct answer is B: Finasteride. Finasteride inhibits 5-alpha reductase, reducing conversion of testosterone to dihydrotestosterone (DHT) in the prostate. This helps shrink the prostate gland, relieving urinary symptoms in BPH. Leuprolide (A) is a GnRH agonist used for prostate cancer. Flutamide (C) is an antiandrogen for prostate cancer. Ketoconazole (D) is an antifungal, not for BPH. Finasteride is the most appropriate choice for this patient based on mechanism of action and indication.

Correct Answer: C

Rationale: The correct answer is C: Gentamycin. Gentamycin is not recommended in this case due to its potential for nephrotoxicity, especially in patients already receiving furosemide. Furosemide is a loop diuretic that can also cause kidney damage, so combining it with Gentamycin increases the risk of further renal impairment. Cotrimoxazole (A) and Ampicillin (D) are commonly used antibiotics that do not have significant interactions with furosemide and Digoxin. Ciprofloxacin (B) is a fluoroquinolone antibiotic that is generally safe to use in patients with CHF and UTI.

Correct Answer:

Rationale: The correct answer is A: renal pelvis. The renal pelvis is not directly related to the action of antidiuretic hormone (ADH) in the nephron. ADH regulates water reabsorption in the collecting duct of the nephron to maintain water balance in the body. Choices B, C, and D are incorrect because they are all associated with the function of ADH in the nephron. ADH regulates the amount of water reabsorbed in the distal tubule and collecting duct, not the renal pelvis.

Correct Answer: B

Rationale: The correct answer is B because a positive dipstick for leucocyte esterase is not 96% specific for >10 wbc/mm³. Leucocyte esterase can indicate the presence of white blood cells, but it does not quantitatively correlate with a specific wbc count. Therefore, it cannot be used to accurately determine the exact wbc count in the urine sample. A: The sensitivity of dipstick for nitrites being 96% means it is good at detecting nitrites, which are a sign of bacterial infection in the urine. C: A bacterial culture with >10^5 colony-forming units has a high probability of representing infection, typically around 95%. D: Blood cultures are not routinely used for diagnosing UTIs; urine culture is the primary method. Blood cultures are more often used for systemic infections.

Correct Answer: A

Rationale: The correct answer is A: the pelvi-ureteric junction. A 1mm renal calculi is most likely to impact at this location because the pelvi-ureteric junction is the narrowest part of the ureter, making it more susceptible to blockages. The size of the calculi is small enough to get lodged at this site, causing obstruction and symptoms. The other choices are incorrect because the vesico-ureteric junction and bladder orifice are wider areas, less likely to be obstructed by a small calculi. The pelvic brim is not a common site for renal calculi obstruction.