What Is Hyponatremia? - Definition, Causes, Symptoms & Treatment

Instructor: Kiley Griffin
In the following lesson you will learn about what hyponatremia as well as what can causes it to occur. You will become familiar with the symptoms and treatment and learn if it is a serious health concern.

Maria has been training to run several marathons in the upcoming year. She decided to visit her friend who lives in Texas for the summer holidays. Maria continued to train even during the hottest days of the summer. She made sure she was drinking water, but she often would feel jittery and nauseous after her runs.

After one run when her muscles started to cramp and she started vomiting, she decided it was time to visit a doctor to make sure there was nothing more serious going on. After taking her history and doing some blood work the doctor came in and told her that she had hyponatremia. Maria has never heard of hyponatremia and does not know what it means for her health and if she should be concerned.

Maria running

What Is Hyponatremia?

Hyponatremia is when there is low sodium in the blood. Sodium is an important electrolyte that helps regulate the water coming into and out of cells. Sodium is important in maintaining blood pressure as well as keeping muscles and other body tissues working properly. Sodium is mostly found in the fluid surrounding cells and when the levels begin to drop and become depleted water flows into the cell. The water flowing into the cell causes it to swell which can cause serious side effects if left untreated. The brain is one organ that is especially susceptible to swelling from severe cases of hyponatremia.

Hyponatremia Causes

Hyponatremia can be caused by many things including both medical conditions and lifestyle factors. Drinking too much water and dehydration can both cause hyponatremia. Drinking too much water can cause low sodium levels in the body, especially if an individual is very active and sweating. When someone sweats, they lose sodium and if too much water is consumed, the sodium levels in the body are diluted. On the other hand, if someone isn't taking in enough fluids and becoming dehydrated, the body loses fluids and electrolytes.

Medical causes of hyponatremia include severe vomiting and diarrhea which causes an individual's electrolytes to become unbalanced. Congestive heart failure can cause fluid to build up in the body. This excess fluid can also cause sodium in the body to become diluted, which leads to hyponatremia. Some kidney and liver diseases can also cause fluids to build up in the body.

Sodium in the cell.~
Sodium Cell

Symptoms of Hyponatremia

Symptoms of hyponatremia include nausea, vomiting and fatigue. It can also cause muscle spasms and weakness as well as irritability and restlessness. More serious symptoms of hyponatremia include confusion, seizures, and coma. These last more severe symptoms occur in severe cases in which the sodium levels drop quickly and the body reacts most often with swelling in the brain.

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