Hyponatremia feedback loop is overwhelmed by increased fluid intake, 2) the feedback loop malfunctions such that ADH is always "turned on"; 3) the receptors in the kidney are always "open" regardless of there being no signal from ADH to be open; or 4) there is an increased ADH even though there is no normal stimulus (elevated serum sodium) for ADH to be increased. Hyponatremia occurs in one of two ways: either the osmoreceptor-aquaporin feedback loop is "overwhelmed", or it is "interrupted". If it is interrupted, it is either "related" or "not related" to ADH. If the feedback system is overwhelmed, this
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