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Maximum Urine Osmolality 1200 — FRCA Primary MCQ

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ModeratePhysiology - RenalMaximum Urine Osmolality 1200FRCA Primary

Regarding renal physiology the maximum concentrating ability of the kidney produces urine with an osmolality of approximately:

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Correct answer: B — 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