Electrolyte test was repeated at least once during treatment of patients with cerebral hemorrhage, normally serum sodium concentration was checked every 2 - 3 days; in severe cases, hyponatremia patients were checked for serum sodium concentration every 24 - 48 hours. Hyponatremia patients (Na + <135 mmol / l) were tested for urinary electrolyte tests (urinarysodium concentration at a moment and / or urinary sodium concentration in the next morning), urine osmotic pressure, blood osmotic pressure.