<prompt> The syndrome of inappropriate ADH secretion is characterized by the following:Hyponatremia and urine sodium excretion 20 mEqLHypernatremia and urine sodium excretion 20 mEqLHyponatremia and hyperkalemiaHypernatremia and hyperkalemia  <response>: In SIADH, the excessive retention of water expands extracellular and intracellular volume. This explains Dilutional Hyponatremia. Since the urine is concentrated hence urine sodium mEqunit of time can be explained. Another plausible explanation is that expanded volume leads to release of ANF and resultant natriuresis explains the urine sodium 20mEqL. Hyponatremia sub-classified according to volume status Clinical example Sodium levels TBW Hypovolemic Hyponatremia Diarrhea Cerebral salt wasting Low Low Euvolemic Hyponatremia SIADH Normal Increased Hypervolemic Hyponatremia CHF Cirrhosis Nephrotic Increase Increased 