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Sodium urine test

  • Definition
    • The sodium urine test measures the amount of sodium in a certain amount of urine.

      Sodium can also be measured in a blood sample.

  • Alternative Names
    • 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 taking any medicines that may affect the test result. Tell your provider about all the medicines you take, including:

      • Corticosteroids
      • Nonsteroidal anti-inflammatory drugs (NSAIDs)
      • Prostaglandins (used to treat conditions such as glaucoma or stomach ulcers)
      • Water pills (diuretics)

      DO NOT stop taking any medicine before talking to your provider.

  • 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 help determine the cause of an abnormal sodium blood level. It also checks whether your kidneys are removing sodium from the body. It may be used to diagnose or monitor many types of kidney diseases.

  • Normal Results
    • 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 provider 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:

  • Risks
    • There are no risks with this test.

  • References
    • Batlle D, Chen S, Haque SK. Physiologic principles in the clinical evaluation of electrolyte, water, and acid-base disorders. In: Alpern RJ, Orson WM, Caplan M, eds. Seldin and Giebisch's The Kidney. 5th ed. Philadelphia, PA: Elsevier Saunders; 2013:chap 74.

      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; 2012: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.