A patient with chronic renal insufficiency weighs 70 kg and has the following laboratory results: creatinine clearance 18 mL/min; potassium 6.8 mEq/L; BUN 75 mg/dL; serum creatinine 6.3 mg/dL. An appropriate dietary modification for the patient is

Correct Answer: B

Rationale: With creatinine clearance 18 mL/min and hyperkalemia (6.8 mEq/L), potassium restriction (2-3 g/day) is critical protein (too high at 70 g), sodium (too low at 1000 mg), and unlimited carbs (diabetes risk) are inappropriate. This distinguishes potassium management, vital for cardiac safety, contrasting with excessive restrictions.

Correct Answer: B

Rationale: Kidney cortex has glomeruli, medulla has pyramids; columns of Bertini (cortical extensions) lie between medullary pyramids not pyramids in cortex or glomeruli in medulla. This distinguishes renal architecture, vital for sectional anatomy, contrasting with misplacements.

Correct Answer: B

Rationale: Adult polycystic kidney disease (ADPKD) is familial, bilateral, asymptomatic until adulthood, and presents with hematuria/hypertension unilateral involvement is rare. This distinguishes ADPKD's bilateral nature, critical for genetics, contrasting with unilateral misconceptions.

Correct Answer: C

Rationale: Proximal tubules reabsorb nearly all filtered glucose (100% normally), not secreted, partial (60-70%), or passively for amino acids (active). This distinguishes PCT's reabsorptive capacity, vital for nutrient retention, contrasting with secretion or partial views.

Correct Answer: D

Rationale: Renin rises with hypovolemia, DCT hyponatremia (macula densa), and sympathetic input not PCT (no sensing role). This distinguishes renin triggers, vital for blood pressure regulation, contrasting with tubular mislocation.