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Sodium (Urine) 

Does this test have other names?

Urine sodium test, Na test

What is this test?

This test measures the amount of salt (sodium) in your urine.

Sodium is in many things you eat. It's found in many processed foods, like pretzels and chips. It's even in some medicines.

Your body needs some sodium to balance other minerals that are in your blood. Sodium is also needed to carry nutrients to different parts of your body. If you have too much sodium, your kidneys absorb it and clear it from your body through urine. But if you have kidney damage, your kidneys may not be able to remove the sodium the way they should. Eating foods with too much sodium can then lead to high blood pressure. This is because the sodium causes your body to hold on to water.

Why do I need this test?

You may need this test if your sodium level is not normal on a blood test. This test helps your healthcare provider find out if you have kidney damage or another condition that can threaten your health.

If you have high blood pressure, your provider may use this test to find out if it's because you have too much salt in your diet. You may also have this test to check for kidney damage. Or it may be done to check on treatment for conditions that affect your sodium levels.

You may also need this test if you have lost a lot of water because of vomiting or diarrhea.

What other tests might I have along with this test?

You may need other urine or blood tests to see how well your kidneys are working and to measure other chemicals in your body. These tests may include:

  • Glomerular filtration rate (GFR) to measure the amount of fluid your kidneys filter

  • Electrolytes

  • Calcium

  • Phosphorus

  • Blood urea nitrogen, or BUN

What do my test results mean?

Test results may vary depending on your age, gender, health history, the method used for the test, and other things. Your test results may not mean you have a problem. Ask your healthcare provider what your test results mean for you.

Results are given in milliequivalents per liter (mEq/L). Normal results for a spot, or one-time, urine sample are 20 mEq/L.

Abnormal results may be caused by:

  • Kidney, heart, or liver problems

  • A condition that affects your thyroid gland

  • Loss of too much water from your body (dehydration)

  • Medicines such as water pills (diuretics)

  • Too much salt in your diet

  • A condition that affects your sodium levels

How is this test done?

This test is done with a urine sample. Your healthcare provider will tell you how to collect the sample.

Does this test pose any risks?

This test poses no known risks.

What might affect my test results?

Eating a diet high in salt or taking medicine for high blood pressure can affect your results. Your results may also be affected if you have had vomiting or diarrhea.

How do I get ready for this test?

You may have to drink a certain amount of water before giving a urine sample. In addition, 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.

Medical Reviewers:

  • Bass, Pat F. III, MD, MPH
  • Haldeman-Englert, Chad, MD