Maximum Urine Osmolality 1200 — FRCA Primary MCQ
Instant feedback + full explanation. One question, done properly.
Educational content. Not a substitute for clinical judgement or local policy.
Reveal the answer and explanation
Correct answer: D — 1200 mOsm/kg
The maximum concentrating ability of the human kidney produces urine of approximately 1200 mOsm/kg (some sources up to 1400). This depends on: intact countercurrent multiplier (loop of Henle) / countercurrent exchanger (vasa recta) / ADH-responsive collecting duct / and adequate medullary interstitial osmolality. Maximum diluting ability produces urine of approximately 50 mOsm/kg.
Reference: Power Kam 2018 Principles of Physiology for the Anaesthetist