A 28-year-old male with a history of recurrent kidney stones presents to the nephrology clinic. Serum osmolality is 295 mOsm/kg and urine osmolality is 150 mOsm/kg despite adequate hydration. The clinician suspects impaired countercurrent multiplication in the loop of Henle. Which investigation would best assess the functional integrity of the countercurrent mechanism?

See the options, answer & explanation

Sign in free to reveal the answer choices, the correct answer, the detailed explanation, and AI-powered insights for this question.