Diagnosis
Laboratory findings in diagnosis of SIADH include:
- Euvolemic hyponatremia <134 mEq/L, and POsm <275 mOsm/kg OR ( POsm - Serum mmol/l < 280 mOsm/kg )
- Urine osmolality >100mOsm/kg of water during hypotonicity
- Urine sodium concentration >40 mEq/L with normal dietary salt intake
Other findings:
- Clinical euvolemia without edema or ascites
- Low blood urea nitrogen (BUN)
- Normal serum creatinine
- Low uric acid
- Normal Acid-Base, K+ balance
- Normal Adrenal, Thyroid function
Read more about this topic: Syndrome Of Inappropriate Antidiuretic Hormone Secretion