Hyponatremia for Everyone. #4. What Happens when Someone has Hyponatremia?

By Second Medical Opinions PLC | SMO Blog Kidney | 23 Nov 2019

Any information or statement present in this post does not replace your health care provider’s advice or treatment. This blog does not provide medical advice, prescribe medications or therapies, or diagnose conditions, it only expresses an opinion. If you have a health-related question or condition, confer with your healthcare provider.

This post appeared here, as part of a series. The author is the same. The series was published as an ebook, which you can find in Amazon Kindle format and Apple Books Format.

When a person develops hyponatremia there are certain changes that occur in the body, specially having to do with the size of the cells and the movement of water in and out of them1. The normal concentration of sodium in the plasma oscillates between 135 mEq/L and 145 mEq/L. When the plasma sodium level decreases below 135 mEq/L, there is an increase in the water concentration in this plasma. Because of this increase in concentration, the water will move from the plasma (extracellular space) into the cells (intracellular space) through the cell membranes, which are semipermeable membranes, therefore susceptible to osmosis. The end result is swollen cells from water moving into the cells in order to to achieve a new equilibrium with its concentration in the intracellular space.

The majority of the tissues can withstand this increase in cellular size. However, there is one tissue where it becomes a problem. This is the the brain tissue. The brain is encased by the cranium, which is a hard structure made of bone. In the event of cell swelling like it happens in hyponatremia, what happens is that some structures may become compressed and there will be an intracranial pressure build up responsible for the signs and symptoms that we will see in the next chapter.