Sodium plays many important roles in the body. It maintains fluid balance and is a main nutrient used in nerve impulse transmission and muscle contraction. The normal range for blood sodium is between 135 and 145 mEq/L (3.10 mg/ml to 3.34 mg/ml). Higher levels of sodium are normally associated with hypertension. A sodium level of 150 mEq/L (3.45 mg/ml) or more is known as hypernatremia, a condition that is commonly caused by dehydration or eating too much salt. However it can also be caused by other conditions such as diabetes or hormonal imbalances.