endocrine and metabolic disorders
Syndrome of Inappropriate ADH Secretion (SIADH)
Introduction
The syndrome of inappropriate ADH (vasopressin) secretion is defined as less than maximally dilute urine in the presence of serum hypo-osmolality, in patients with normal adrenal, thyroid, renal, hepatic, and cardiac function who do not have hypotension, volume depletion, or other physiologic causes ofvasopressinsecretion. SIADH is associated with myriad disorders. Hyponatremia is the result, and symptoms are those of hyponatremia. Diagnosis is by measurement of serum and urine osmolality and electrolytes. Treatment is with water restriction, sometimes with oral or intravenoussodium chloride, and rarely withvasopressinreceptor antagonist medications such asconivaptanortolvaptan. SIADH can cause significant Hyponatremia . (See also Water and Sodium Balance .) 