All are true regarding SIADH, except -
Ans. is 'b' i.e., Urine hypoosmolar Cardinal features of SIADH include:o Hyponatremia (dilutional hyponatremia with Na+ < 135 m mold).o Decreased plasma osmolality (<280 m osm/kg with inappropriately increased urine osmolality > 150 m osm).o High urine sodium (over 20 meq/l).o Low blood urea Nitrogen <10 mg/L.o Hypouricemia (< 4 mg/dL).o Clinical Euvolemia.Absence of signs of hypervolemia (edema, ascitis).Absence of signs of hypovolemia (orthostatic hypotension, tachycardia, features of dehydration),o Absence of cardiac, liver or renal disease.o Normal thyroid and adrenal function.o A high BUN suggests a vloume contracted state and excludes a diagnosis of SIADH2.Syndrome of Inappropriate ADH Secretion (SIADH) :CRITERIA FOR DLAGNOSISCriteria for the diagnosis of syndrome of inappropriate antidiuretic hormone secretionEssentialo Decreased effective osmolality of the extracellular fluid (POSM< 275 m Osmol/kg H,0). (True hypoosmolality must be present and hyponatremia secondary to pseudohypomatremia or hyperglycemia must be excluded).o Inappropriate urinary concentration (Uosm > 100 mOsmo/kg H2O with normal renal function) at some level of hypoosmolarity. (Urinary concentration must be inappropriate for Plasma Hypos molality),o Clinical envolemia, as defined by the absence of signs of hypovolemia (orthostasis, tachycardia, decreased skin rurgor, dry mucous membranes) or hypervolemia (subcutaneous edema, ascites),o Elevated urinary sodium excretion while on normal salt and water intake.o Absence of other potential causes of euvolemic hypoosmolality: Hypothyroidism, hypocortisolism (Addison's disease or pituitary' adrenocorticotropic hormone insufficiency) and diuretic use.Supplementalo Abnormal water load test (inability' to excrete at least 90% of a 20 ml/kg water load in 4 hours and/or failure to dilute Uosm to < 100 mOsmol/kg H2O).o Plasma AVP level inappropriately elevated relative to plasma osmolality.o No significant correction of serum with volume expansion but improvement after fluid restriction.
Increased level of ADH (AHMS Nov 93)
Urine hvpoosmolar
Hyponatremia
Adequate hydration status
Endocrinology