Which is the most common cause of these renal causes of acute renal failure?

Correct Answer: A

Rationale: Ischemic ATN is the most common renal ARF cause hypoperfusion (e.g., shock) damages tubules, outpacing nephrotoxic ATN (drugs), tubulointerstitial nephritis (allergic), and renal artery stenosis (vascular). Ischemia's frequency distinguishes it, critical for hospital-acquired ARF, unlike toxin, immune, or arterial causes.

Correct Answer: D

Rationale: Pigment gallstones are radiopaque (~50%) calcium bilirubinate, visible on X-ray, unlike urate (radiolucent), cholesterol (bile, rare), or struvite (renal, not bile). Gallbladder context fits common site. Radiopacity distinguishes it, key to imaging detection, unlike ureteral or mislocated stones.

Correct Answer: C

Rationale: Azithromycin 1 g + ofloxacin 400 mg once treats urethritis (e.g., Chlamydia/gonorrhea) in young males with dysuria 5-10 WBC fits STD, most appropriate. Ciprofloxacin 2 weeks is pyelonephritis overkill. TMP-SMX 3 days is female UTI short. Cephalexin 7 days lacks STD coverage mismatch. STD regimen distinguishes it, key to age/context, unlike UTI-focused options.

Correct Answer: D

Rationale: Chronic glomerulonephritis features hyalinized glomeruli, granular subcapsular surface, shrunken kidneys, and prior disease history not normal calyces, enlargement, or no history. Hyalinization marks end-stage scarring, critical for diagnosis, contrasting with acute features like normal surfaces or enlarged kidneys typical of early inflammation.

Correct Answer: D

Rationale: Medullipin I (hypotensive) isn't linked to peritubular capillary endothelium, unlike PCT (brush border), bladder (transitional), DCT (macula densa), and afferent arterioles (renin). This corrects renal associations, key for physiology, contrasting with true pairings.