Sodium is the primary cation in extracellular fluids in animals and humans. It is vital to normal body processes, which include nerve and muscle functioning. Sodium levels in the body are partly controlled by aldosterone, which is made by the adrenal glands. LOW levels of blood sodium indicate hyponatremia, which is usually due to too much sodium loss, too much water intake or retention, or edema. Symptoms may include weakness, fatigue, confusion, and in severe cases fall into a coma. Hyponatremia is rarely due to decreased sodium intake; most commonly, it is due to sodium loss (Addisons disease, diarrhea, excessive sweating, diuretic administration, or kidney disease). HIGH blood sodium level indicates hypernatremia and is almost always due to dehydration without enough water intake. Symptoms include dry mucous membranes, thirst, agitation, restlessness, acting irrationally, and coma or convulsions if levels rise extremely high. In rare cases, hypernatremia may be due to increased salt intake without enough water, Cushing syndrome, or a condition caused by too little ADH, called diabetes insipidus.