Evaluation of Volume and Electrolyte Balance in Hyponatremia Treatment - a Prospective Observational Trial

Inclusion Criteria: * Adult patients ≥ 18 years * Hypotonic hyponatremia * glucose-corrected plasma sodium \<130 mmol/l * serum osmolality \<280 mosmol/kg or lack of signs of non-hypotonic hyponatremia Exclusion Criteria: * Signs of extracellular volume expansion * Patients with liver cirrhosis and severe liver damage AST/ALT\>3xULN, AP\>6xULN, Bilirubin ≥ 3mg/dl * Patients with heart failure * Patients on dialysis and/or patients with oliguric renal impairment and plasma creatinine ≥ 3mg/dl * Patients after organ transplantation