====== Hypotonic hyponatremia ======

Hypoosmolar [[hyponatremia]] is a condition where [[hyponatremia]] associated with a low [[plasma osmolality]]. The term "hypoosmolar hyponatremia" is also sometimes used.

When the [[plasma osmolality]] is low, the extracellular fluid volume status may be in one of three states: low volume, normal volume, or high volume.
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[[SIADH]]: [[hypotonic hyponatremia]] (efective serum [[osmolality]] <275 mOsm/L) within appropriately high urinary concentration (urine osmol>100 mOsm/L) and [[euvolemia]] or [[hypervolemia]].