A patient is admitted to the ICU after a motor vehicle accident. On the second day of the hospital admission, the patient develops acute kidney injury. The patient is hemodynamically unstable, but renal replacement therapy is needed to manage the patients hypervolemia and hyperkalemia. Which of the following therapies will the patients hemodynamic status best tolerate?

Correct Answer: C

Rationale: CVVHD facilitates the removal of uremic toxins and fluid. The hemodynamic effects of CVVHD are usually mild in comparison to hemodialysis, so CVVHD is best tolerated by an unstable patient. Peritoneal dialysis is not the best choice, as the patient may have sustained abdominal injuries during the accident and catheter placement would be risky. Plasmapheresis does not achieve fluid removal and electrolyte balance.

Correct Answer: C

Rationale: The collecting duct (C) becomes water-permeable with ADH via aquaporin-2, concentrating urine. The proximal tubule (A) and descending limb (B) are always permeable, and ascending limb (D) is not, making C the ADH-dependent match.

Correct Answer: A

Rationale: Inhibiting Na⁺ reabsorption in the PCT (A) reduces water reabsorption, increasing urine output (diuresis). Decreased output (B) contradicts this, and bilirubin (C) or fat (D) effects are unrelated to sodium, making A correct.

Correct Answer: D

Rationale: C₆H₁₂O₆ (glucose) in urine (D) is abnormal (glycosuria) as it's filtered and reabsorbed, not secreted, unless the threshold is exceeded (e.g., diabetes). Normal (A, B) or secreted (C) options misalign, making D correct.

Correct Answer: A

Rationale: pH, specific gravity, and glucose within normal ranges indicate typical urinalysis results.