Inclusion Criteria:  Acute ischemic stroke diagnosed by the clinical presentations and brain imaging is confirmed by a stroke care specialist. has a measurable neurologic deficit according to the National Institutes of Health Stroke Scale (NIHSS) the time between the onset of neurological symptoms and starting therapy are less than 24 hours admission BUN/Cr≧15  Exclusion Criteria:  no informed consent obtained initial NIHSS >10 prepared for or received fibrinolytic therapy prepared for or received surgical intervention with 14 days congestive heart failure according to past history or Framingham criteria history of liver cirrhosis or severe liver dysfunction (ALT or AST > x 3 upper normal limit) admission blood Cr >2 mg/dl initial blood pressure SBP<90 mmHg fever with core temperature >=38°C indication of diuretics for fluid overload any conditions needed more aggressive hydration or blood transfusion cancer under treatment life expectancy or any reasons for follow-up < 3 months