A patient has very high plasma uric acid and has high risk of developing acute * uric acid nephropathy. Which of the following agent should be avoided?

Correct Answer: B

Rationale: The correct answer is B: Acetazolamide. Acetazolamide is a carbonic anhydrase inhibitor that can worsen hyperuricemia by increasing renal uric acid reabsorption. This can further exacerbate the risk of acute uric acid nephropathy. Ethacrynic acid (A), Hydrochlorothiazide (C), and Furosemide (D) are loop diuretics that can actually help in reducing uric acid levels by increasing its excretion through the urine. Therefore, they would not be contraindicated in this scenario.

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.

Correct Answer: D

Rationale: The correct answer is D: The cremaster muscle contracts in response to cold and draws the testicles closer to the body. This is true because the cremaster muscle is responsible for regulating the position of the testicles in response to temperature changes to maintain optimal conditions for sperm production. The other choices are incorrect because: A: The lymphatic vessels of the testes drain into the para-aortic lymph nodes, not the abdominal lymph nodes. B: The vas deferens is a duct that carries sperm from the testes to the urethra, not located along the inferior portion of each testis. C: The difference in height between the testes is due to differences in the descent of the testes during fetal development, not the length of the spermatic cord.