Often sodium is not seen as a helpful nutrient. Although it has a bad reputation, sodium is actually a very essential electrolyte. Together with potassium, sodium balances fluids in the body. At the same time sodium influences blood pressure regulation, heart rhythm, muscle contraction, and nerve impulse transmission. Because sodium is so essential, the body has built-in mechanisms for keeping blood levels within a very tight range. Blood sodium is regulated by the kidneys and hormones produced by the adrenal glands and the pituitary gland.
Unusual serum sodium levels can indicate an underlying medical condition like Cushing’s syndrome (overactive adrenal glands) or Addison’s disease (underactive adrenal glands). Unbalanced sodium levels are also very often related to the body’s hydration status, meaning dehydration or overhydration.
When there is an excess of water in the body, sodium becomes diluted, resulting in low sodium levels in the blood, or hyponatremia. It does not happen often, but it is possible, for hyponatremia to be caused by drinking too much water. Cases of this have been seen as a result of water-drinking contests, a hazing ritual used by some fraternities in the U.S.. On the other side, when the body does not have enough water (is dehydrated), there is a relative surplus of sodium in the blood, which is known as hypernatremia. This condition may occur as a result of not drinking enough water or excessive sweating. It is seen most frequently among the elderly, since the thirst mechanism declines with age. Therefore, elderly people are urged to drink water even if they do not feel thirsty to avoid becoming dehydrated and developing hypernatremia, which can be fatal in very severe cases.
Although “salt” and “sodium” are often used interchangeably, they are not the same. Table salt is actually sodium chloride, a specific type of sodium obtained through the diet rather than produced naturally by the body.
Sodium levels are measured on a routine basic metabolic panel test, but a separate blood sodium test may also be ordered if a person displays symptoms of hypernatremia or hyponatremia.
If a blood test shows an abnormal sodium level, a urine test may be used to determine the cause if the imbalance.