Risks

There is no chance for problems in collecting a one-time or 24-hour urine sample.

Results

A test for sodium in the urine is a 24-hour test or a one-time (spot) test that checks how much sodium is in the urine. Sodium is both an electrolyte and a mineral.

Normal

The normal values listed here-called a reference range-are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what’s normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

Results are ready in 1 day.

Many conditions can affect sodium levels. Your doctor will talk with you about any abnormal results that may be related to your symptoms and past health.

What Affects the Test

Reasons you may not be able to have the test or why the results may not be helpful include:

• Taking medicines, such as birth control pills, corticosteroids, antibiotics, estrogens, tricyclic antidepressants, heparin, nonsteroidal anti-inflammatory drugs (NSAIDs), diuretics, lithium, and many medicines used to treat high blood pressure.
• Having high levels of glucose, triglycerides, or protein.
• Getting sodium in intravenous (IV) fluids given during a recent surgery or hospitalization.

What To Think About

• Sodium levels can also be measured in a blood test. For more information, see the topic Sodium (Na) in Blood.
• Doctors may look at urine sodium and blood sodium levels to see whether conditions or medicines may be causing fluid or electrolyte imbalances. Urine sodium levels are often high when blood levels are low or low when blood levels are high. Urine sodium levels are affected by medicines and hormones.
• To see whether the body is passing too little or too much sodium in the urine, a value called the fractional excretion of sodium (FENa) can be found by looking at the amounts of sodium and creatinine in blood and urine. In a person with kidney failure, a low FENa may mean less blood flow to the kidneys is causing the kidney failure.