Syndrome of Inappropriate Antidiuretic Hormone Secretion
Basic Information
Definition
Syndrome of inappropriate antidiuretic hormone secretion (SIADH) is a dilutional hyponatremia associated with increased renal water retention. It is defined by a plasma sodium level less than 130 mmol/L, plasma osmolality less than 280 mOsm/L, urine sodium level more than 25 mmol/L, urine osmolality greater than the plasma osmolality, absence of edema or volume depletion, and normal renal and adrenal function.
Epidemiology & Demographics
• Hyponatremia is the most common electrolyte disorder seen in clinical medicine, affecting 15% of hospitalized patients. SIADH is one of the most common causes of euvolemic hyponatremia.
