The apex of the renal pyramid is called the:

Correct Answer: C

Rationale: Renal papilla is the pyramid apex draining into calyces, not calyx or pelvis. This specifies medullary tip, key for urine collection, contrasting with collecting structures.

Correct Answer: D

Rationale: Cyclosporine toxicity is common, not rare narrow therapeutic window, unpredictable levels (e.g., nephrotoxicity), incorrect. Identical twins need no immunosuppression genetic match, true. Rejection symptoms (tenderness, oliguria, creatinine rise) classic, accurate. Infection's early dominance (80% in year 1) correct. Toxicity's frequency distinguishes the error, critical for transplant management, unlike true donor, rejection, or infection statements.

Correct Answer: B

Rationale: 12-18 years is the peak for testicular torsion pubertal growth (bell-clapper deformity) increases risk, most common. <10 years occurs less frequent. 20-25 wanes still possible. 30-50 is rare adult decline. Adolescent predominance distinguishes it, critical for emergency recognition, unlike younger or older groups.

Correct Answer: B

Rationale: Plain AXR has marginal value in renal colic not cost-effective, replaced by non-contrast CT (~95% sensitivity). Always doing it wastes resources CT superior. Majority shown (~80%) still misses urate. Low sensitivity (~50-60%) is true but not the full reason CT rules. Marginal utility distinguishes it, key to modern imaging shift, unlike routine or partial truths.

Correct Answer: D

Rationale: ~60% renal function (GFR) can be lost with normal creatinine compensatory hypertrophy masks decline (e.g., GFR 120 to 50 mL/min), nonlinear rise. 20-50% underestimates creatinine lags. 60% distinguishes it, critical for early CKD detection, unlike lower estimates.