Because of the high prevalence of cardiovascular disease, doctors always instruct patients to eat a low-salt diet, which is necessary for patients with heart failure patients with renal failure, but for some patients it may not be right. Have encountered a few elderly patients, because found to have mild hypertension and change their habit of eating salt, as a result, within six months of the emergence of limb weakness, gradually mental trance, followed by limb tremor, magnetic resonance imaging found that the brain multiple lamellar foci, electrolyte examination is hyponatremia, sodium supplementation to the patient’s treatment for one day that is greatly improved, three days after the disease over. And this situation is not less, so we need to analyze the specific problems.