Sodium urine test
The sodium urine test measures the amount of salt (sodium) in a urine sample.
Sodium can also be measured in a blood sample.
Urinary 24 hours sodium; Urine Na+
How the test is performed
After you provide a urine sample, it is tested in the lab. If needed, the health care provider may ask you to collect your urine at home over 24 hours. Your provider will tell you how to do this. Follow instructions exactly so that the results are accurate.
How to prepare for the test
Your health care provider will ask you to temporarily stop any medicines that may affect the test results. Be sure to tell your provider about all the medicines you take. These include:
- Nonsteroidal anti-inflammatory drugs (NSAIDs)
- Prostaglandins (used to treat for example, glaucoma or stomach ulcers)
- Water pills (diuretics)
- Do not stop taking any medicine before talking to your doctor.
How the test will feel
The test involves only normal urination. There is no discomfort.
Why the test is performed
The test is often used to check how much fluid your body has. It also checks if your kidneys are able to maintain or remove sodium from the urine. It may be used to diagnose or monitor many types of kidney diseases.
For adults, normal urine sodium values are generally 20 mEq/L in a random urine sample and 40 to 220 mEq/L per day (mEq/L/day). Your result depends on how much fluid and salt you take in.
The examples above are common measurements for results of these tests. Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test result.
What abnormal results mean
A higher than normal urine sodium level may be due to:
- Certain medicines such as water pills (diuretics)
- Low function of the adrenal glands
- Inflammation of the kidney that results in salt loss (salt-losing nephropathy)
- Too much salt in the diet
A lower than normal urine sodium level may be a sign of:
- Adrenal glands releasing too much hormone (hyperaldosteronism)
- Not enough fluid in the body (dehydration)
- Diarrhea and fluid loss
- Heart failure
- Kidney problems such as chronic kidney disease or kidney failure
- Scarring of the liver (cirrhosis)
What the risks are
There are no risks with this test.
Gerber GS, Brendler CB. Evaluation of the urologic patient: history, physical examination, and urinalysis. In: Wein AJ, Kavoussi LR, Novick AC, et al., eds. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 3.
McPherson RA, Ben-Ezra J. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 28.