Effective serum osmolality <275 mOsm/kg
Urine specific gravity > 1.015
Urine osmolality >100 mOsm/kg at some level of decreased effective osmolality
Clinical euvolemia
Urine sodium concentration >30 mmol/l with normal dietary salt and water intake
Absence of adrenal, thyroid, pituitary or renal insufficiency
No recent use of diuretic agents
Serum uric acid <0.24 mmol/l (<4mg/dl)
Serum urea <3.6 mmol/l (<21.6mg/dl)
Failure to correct hyponatremia after 0.9% saline infusion
Fractional sodium excretion >0.5%
Fractional urea excretion >55%
Fractional uric acid excretion >12%
Correction of hyponatremia through fluid restriction
Syndrome of inappropriate antidiuretic hormone secretion
Inappropriate or hypersecretion from hypothalamus
Adrenal crisis
Infectious
Thyrotoxic periodic paralysis
Brain abscess
Diabetic ketoacidosis
Encephalitis, meningitis