Electrolyte Disturbances (Assessment & Diagnosis) — 72yo Man | Nephrology | MCCQE1 Q#13301

MCCQE1 Question #13301

Dimension of Care

Acute Care

Activity

Assessment & Diagnosis

Objective

Electrolyte Disturbances

Section

Medicine / Family Medicine

Subject

Nephrology

Last updated: February 2026
A 72-year-old man is admitted with community-acquired pneumonia and is receiving IV antibiotics. On day 2, he becomes mildly confused but remains hemodynamically stable. He reports drinking large amounts of free water because of dry mouth. Past history includes hypertension and osteoarthritis, treated with hydrochlorothiazide, amlodipine, and acetaminophen. Examination shows no peripheral edema, moist mucous membranes, and no orthostatic symptoms. Laboratory studies reveal hypotonic hyponatremia. Which investigation set is most appropriate to help establish the underlying etiology of this patient’s hyponatremia?
Full answer analysis and choices are available inside the practice session.