Question: The syndrome of inadequate secretion of antidiuretic hormone (SIADH) is characterized by: 
 Options:  <1> Hyponatremia <2> Hypovolemia <3> Concentrations of sodium ion in urine less than 20 mmol / L. <4> Osmolality in urine less than serum osmolality. <5> High concentrations of calcium ion.
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