<prompt> Syndrome of inappropriate antidiuretic hormone secretion is diagnosed by all EXCEPT:HyponatremiaDecreased osmolality 280 mosmkgNormal blood nitrogenNormal thyroid function  <response>: Cl Normal blood urea nitrogen 2102-H 16lh 769-70-CMDT-2009 277-78-H17th Syndrome of inappropriate antidiuretic hormone secretion SIADHClinical features Hyponatremia Decreased osmolality 280 mosmkg with inappropriately increased urine osmolalilty 150 mosmkg Absence of cardiac, renal or liver disease Normal thyroid and adrenal function Urine sodium usually over 20 mEqL.Other changes Low blood urea nitrogen BUN 10 mgdL Hypouricemia 4 mgdL A high BUN suggests a volume state, which excludes a diagnosis of SIADH. 