Effects of Low Blood Sodium Levels on Blood Pressure

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Sodium plays a critical role in the regulation of your major bodily functions. How much or how little fluid you retain, as well as the functioning of your nervous system and your muscles all depend on sodium. The 2010 Dietary Guidelines for American published by the U.S. Department of Health and Human Services and the USDA recommend reducing added salt in your daily diet to help avoid high blood pressure. Although high blood sodium blood levels can increase your blood pressure, extremely low blood sodium levels might be the result of years of chronic hypertension and cardiovascular disease.

Normal Function

Sodium's presence in the bloodstream and kidneys provide signals to your kidneys for the amount of sodium and urine to excrete. When the kidneys sense low sodium, they lower the amount of sodium they remove from your body by restricting the urine produced. When your kidneys hold on to liquid, blood volume increases, and eventually so does your blood pressure. Conversely, when you consume a large amount of sodium, your kidneys work to excrete more urine and along with it, excess salt. If you have sensitivity to it, or existing conditions, moderate to high loads of salt can overload your system and lead to chronic problems.

Excess Fluid Intake

When you drink water, you hydrate your body and increase your blood volume as a secondary effect. Ordinarily, your kidneys excrete some of the liquid as urine, and no harm results. When you drink copious amounts of water, though, you dilute the salt in your bodily fluids. Sensing the lower concentration of salt, your kidneys hold on to fluid in an attempt to prevent sodium loss. Increased blood volume leads to high blood pressure and swollen tissues. If you continue to drink large volumes of water, water intoxication results. Dangerously low levels of sodium, combined with excess amounts of fluid can lead to organ failure, swelling of the brain and death. Water intoxication can be accidental or intentional. In 2007, a woman died after entering a water-drinking competition and suffering water intoxication, according to an October 9, 2009 article in L.A. Now.

Systemic Problems

Serious health problems such as heart failure and kidney failure can lead to a condition known as hyponatremia, or low blood sodium levels. Older people in failing health, or those with heart failure, insufficient blood supply to the kidneys, liver damage or other significant health issues can develop abnormally low blood sodium levels when their bodies retain too much fluid due to organ failure or complications from medications. The resulting low sodium levels further lead to unstable blood pressure, edema or swelling and other problems.


More than just raising blood pressure pursuant to accumulated body fluids, very low blood sodium levels and the resulting chemical imbalance in your blood can cause confusion, headaches, nausea or even coma and death. A moderate to low sodium diet helps protect you from the chronic conditions caused by too much sodium, including high blood pressure, blood vessel disease, and heart and kidney failure. The 2010 Guidelines for Americans recommends a maximum daily sodium intake of 2,300 mg for healthy adults under 51 years of age, and less than 1,500 mg for anyone 51 or older, who is sodium-sensitive or has existing conditions, such as heart or kidney disease.

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