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Why Low Sodium is Not Always a Good Thing When it Comes to Blood Tests

written by: weborglodge•edited by: Emma Lloyd•updated: 5/4/2010

Many people need to eat less salt to reduce blood pressure or prevent swelling. However, some people don't realize that low sodium in blood tests indicates a potential problem with the kidneys or other organs.

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    Importance of Sodium

    Sodium is the most abundant cation or positively charged ion in your body's tissues and fluids. Essentially, all life processes are chemical reactions which take place at the cellular level. Sodium is important for those reactions which occur in your nerve and muscle cells.

    Sodium also affects how your body retains water. Your body exists in a state of equilibrium between your blood vessels, organ systems, and the surrounding tissues. If you take in too much salt, your body will retain water to restore the proper concentration of electrolytes and water in your system. Sometimes, certain conditions whether temporary or chronic can cause imbalances which show up as low sodium in blood tests.

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    Causes of Low Sodium

    Usually, your body does a good job of maintaining proper levels of sodium. However, if you are taking diuretics or drinking too much water, you can cause your body to excrete high levels of sodium, resulting in low blood sodium levels.

    Conditions such as Syndrome of Inappropriate Anti-Diuretic Hormone (SIADH) cause the reverse effect. Rather than reducing your blood's concentration of sodium through urination, blood concentrations drop due to retaining water caused by an abundance of anti-diuretic hormones. Anti-diuretic drugs may be prescribed as part of cancer treatment plans and cause similar effects.

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    Symptoms of Low Sodium

    Unless you have a severe case, chances are you may not have overt symptoms. The only way you may find out is if there is low sodium in blood tests. If you do experience symptoms, they may include headaches and nausea. You may also feel drowsy or have moments of confusion as your body struggles to perform while deficient in this vital mineral.

    If you complain of such signs, your doctor will likely order blood tests in order to determine your blood chemistry. Symptoms such as confusion and headaches indicate that your brain is somehow affected, which may prompt your doctor to take this course of action. Normal sodium levels range from 136 to 145 mEq/L. Sodium and other electrolyte levels can be detected by running a profile test on a small blood draw. The test will show the normal ranges and where you fall within these spans. Test results are typically available the same day or the following.

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    Treatment Options

    How much you drink can affect your blood sodium levels. Your doctor may make changes in your diet which affect how much you drink or the amount of sodium in which you ingest. If diuretics or other medications are causing your hyponatremia, she may recommend changes in your dosage levels.

    She may also recommend electrolyte replacement in order to quickly restore proper levels. Treatment is imperative as severe cases can cause swelling of the brain, which can lead to fatal consequences.

    Because of its role in your body's functioning, proper levels of blood sodium are important for your good health. If you have any of the risk factors because of the medication your take or pre-existing conditions, make sure and discuss regular testing to keep track of your sodium levels. Your life may depend upon it.

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    Chemo Care: Hyponatremia (Low Sodium) –

    Sherwood, Lauralee. Human Physiology: From Cells to Systems. 2008