Does this test have other names?
What is this test?
This test measures the levels of sodium in your blood. Sodium is a substance your
body's cells need to work normally. Sodium helps make sure that your nerves and muscles
can work as they should. Sodium is also important because it helps maintain the right
balance of fluids in your body. The kidneys help keep sodium at a healthy level. You
can get the sodium you need through your diet. But it's easy to take in too much sodium
through your diet. When your body has too much sodium, your kidneys can't remove enough
of it. Sodium collects in your bloodstream. This can lead to high blood pressure,
which can cause other problems.
Too much sodium in the blood is called hypernatremia. Too little sodium in the blood
is called hyponatremia. Hypernatremia can occur when you lose too many fluids. This
can happen from sweating too much, vomiting, or diarrhea. Hyponatremia can occur when
you drink large amounts of water or if you have problems with your kidneys that affect
your ability to urinate.
Why do I need this test?
You may need this test if your healthcare provider thinks you have an imbalance of
fluids and sodium. You may have symptoms such as:
Problems with mental or cognitive function
Muscle cramps or twitching
Cravings for large amounts of salt
Confusion or forgetfulness
Problems with walking
General unwell feeling
Shortness of breath
Fluid buildup or swelling in part of the body
The test can check for:
Or you may need this test if you:
Are taking certain medicines, such as water pills (diuretics)
Are having sodium therapy
Lost a large amounts of bodily fluids
You may also have this test as part of a routine health check.
What other tests might I have along with this test?
You may need other tests along with a sodium blood test. You may have tests to look
Other electrolyte levels in your blood, such as potassium
Concentration of your urine
Level of sodium in your urine
Concentration of your blood
Levels of uric acid and urea
Acid-base balance in your blood
What do my test results mean?
Test results may vary depending on your age, gender, health history, and other things.
Your test results may be different depending on the lab used. They may not mean you
have a problem. Ask your healthcare provider what your test results mean for you.
Normal sodium levels are usually between 136 and 145 millimoles per liter (mmol/L).
Blood sodium levels below 136 mmol/L may mean you have low blood sodium (hyponatremia).
Blood sodium levels greater than 145 mmol/L may mean you have blood sodium levels
that are too high (hypernatremia).
How is this test done?
The test is done with a blood sample. A needle is used to draw blood from a vein in
your arm or hand.
Does this test pose any risks?
Having a blood test with a needle carries some risks. These include bleeding, infection,
bruising, and feeling lightheaded. When the needle pricks your arm or hand, you may
feel a slight sting or pain. Afterward, the site may be sore.
What can affect my test results?
If your blood sample is collected incorrectly, your test results may be affected.
Having high blood sugar (hyperglycemia) can also affect your test results.
Taking some medicines can also affect your test results. These include diuretics and
nonsteroidal anti-inflammatory medicines, such as ibuprofen.
How do I get ready for this test?
Your healthcare provider will tell you what you need to do before this test. You may
need to not eat or drink for several hours before the test. You may need to skip or
delay certain medicines on the day of the test. Be sure your healthcare provider knows
about all medicines, herbs, vitamins, and supplements you are taking. This includes
medicines that don't need a prescription and any illegal drugs you may use.