Sodium (Urine) 

Does this test have other names?

Urine sodium test, urine 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 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:

  • Sodium level in the blood

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

  • Other electrolytes, such as potassium

  • Calcium

  • Phosphorus

  • Blood urea nitrogen (BUN)

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.

Results are given in milliequivalents per liter (mEq/L). Normal results for a spot, or one-time, urine sample are 20 mEq/L. Normal results for a 24-hour urine sample range from 40 mEq/L to 220 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. For a 24-hour urine sample, you must collect all your urine for 24 hours. Empty your bladder completely first thing in the morning without collecting it. Note the time. Then collect your urine every time you go to the bathroom over the next 24 hours. Place the sample in the container that your healthcare provider or the lab gives you.

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 the medicines, herbs, vitamins, and supplements you are taking. This includes medicines that don't need a prescription and any illegal drugs you may use.

Online Medical Reviewer: Chad Haldeman-Englert MD
Online Medical Reviewer: Raymond Turley Jr PA-C
Online Medical Reviewer: Tara Novick BSN MSN
Date Last Reviewed: 9/1/2022
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