A 70-year-old man admitted to the intensive care unit (ICU) for sepsis was recently given a diagnosis of syndrome of inappropriate antidiuresis. His serum sodium acutely fell from 130 mEq to 115 mEq/L during the past 3 days, and he recently seized secondarily to this problem. Which would be the most appropriate treatment option?

Correct Answer: C

Rationale: Severe symptomatic hyponatremia (e.g., seizures) due to SIADH requires rapid correction with hypertonic saline (3% sodium chloride) to increase serum sodium safely and prevent further neurological complications.

Correct Answer: D

Rationale: Shrinking hepatocytes due to high osmolarity trigger glycogen and protein breakdown to release solutes and maintain cell volume.

Correct Answer: A

Rationale: Vasopressin (ADH) increases water permeability in the collecting ducts, promoting reabsorption.

Correct Answer: C

Rationale: Vasopressin, secreted by the posterior pituitary, promotes water reabsorption in the kidneys.

Correct Answer: C

Rationale: Angiotensin-converting enzyme (ACE) converts angiotensin I to angiotensin II in the lungs.