<prompt> SIADH featureHyponatremia with sodium excretion 20 mEqLHypernatremia with hypokalemiaHypernatremia with Na excretion 20 mEqLHyponatremia with hyperkalemia  <response>: A Hyponatremia with sodium excretion 20mEql Syndrome of Inappropriate Antidiuretic Hormone ADH secretion SIADH is defined by the hyponatremia and hypo-osmolality resulting from inappropriate, continued secretion or action of the hormone despite normal or increased plasma volume, which results in impaired water excretion. Diagnosis: In the absence of a single laboratory test to confirm the diagnosis, SIADH is best defined by the classic Bartter-Schwartz criteria, which can be summarized as follows: Hyponatremia with corresponding hypo-osmolality Continued renal excretion of sodium Urine less than maximally dilute Absence of clinical evidence of volume depletion Absence of other causes of hyponatremia Correction of hyponatremia by fluid restriction Cardinal features of SIADH include: Hyponatermia dilutional hyponetremia with Na 135 mmoll Decreased plasma osmolality 280 m osmkg with inappropriately increased urine osmolality 150 m osm. Urine sodium over 20 meql Low Blood urea Nitrogen WmgL Hypouricemia 4mgdL, Absence of cardiac, liver or renal disease, Normal thyroid and adrenal function A high BUN suggests a volume contracted state and excludes a diagnosis of SIADH. 