hormonal and metabolic disorders
Syndrome of Inappropriate Secretion of Antidiuretic Hormone (SIADH)
Introduction
The syndrome of inappropriate secretion of antidiuretic hormone develops when too much antidiuretic hormone (vasopressin) is released by the pituitary gland under certain inappropriate conditions, causing the body to retain fluid and lower the blood sodium level by dilution. (See also Overview of Electrolytes and decreases water excretion by the kidneys. As a result, more water is retained in the body, which dilutes the level of sodium in the body. A low level of sodium in the blood is called Hyponatremia (Low Level of Sodium in the Blood) . The pituitary gland appropriately produces and releasesvasopressinwhen the blood volume (amount of fluid in the blood vessels) or blood pressure goes down or when levels of electrolytes (such as sodium) become too high. Secretion ofvasopressinis termed inappropriate if it occurs when Blood volume is normal or high Blood pressure is normal or high Hyponatremia (Low Level of Sodium in the Blood) None Other appropriate reasons forvasopressinrelease are not present Whenvasopressinis released in these situations, the body retains too much fluid, and the sodium level in blood decreases. 