Hypotonic hyponatremia Hypotonic hyponatremia Hypoosmolar hyponatremia is a condition where hyponatremia associated with a low plasma osmolality. The term "hypotonic hyponatremia" is also sometimes used. When the plasma osmolarity is low, the extracellular fluid volume status may be in one of three states: low volume, normal volume, or high volume. Loss of water is accompanied by loss of sodium. Treat underlying cause and give IV isotonic saline. It is important to note that sudden restoration of blood volume to normal will turn off the stimulus for continued ADH secretion. Hence, a prompt water diuresis will occur. This can cause a sudden and
Hypotonic hyponatremia blood volume that is no longer there, that has been lost from the body. As a result, their blood volume is reduced. As mentioned above, lack of adequate blood volume is a potent stimulus for ADH secretion and thence water retention. Some patients with hyponatremia have normal or slightly elevated blood volume. In those patients, the increased ADH activity and subsequent water retention may be due to "physiologic" causes of ADH release such as pain or nausea. Alternatively, they may have the Syndrome of Inappropriate ADH (SIADH). SIADH represents the sustained, non-physiologic release of ADH and most often occurs as