Sodium urine test
Definition
The sodium urine test measures the amount of sodium in the 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, your 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 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 more than 20 mEq/L in a random urine sample and 40 to 220 mEq (40 to 220 mmol) per day. Your result depends on how much fluid and sodium or salt you take in.
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:
- Adrenal glands releasing too much aldosterone (hyperaldosteronism)
- Not enough fluid in the body (dehydration)
- Diarrhea and fluid loss
- Heart failure
- Kidney problems, such as long-term (chronic) kidney disease or kidney failure
- Scarring of the liver (cirrhosis)
Risks
There are no risks with this test.
References
Al-Awqati Q, Radhakrishnan J. Disorders of sodium and water. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 102.
Gharavi AG, Landry DW. Approach to the patient with renal disease. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 100.
Kamel KS, Halperin ML. Interpretation of electrolyte and acid-base parameters in blood and urine. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 24.
Oh MS, Briefel G, Pincus MR. Evaluation of renal function, water, electrolytes, and acid-base balance. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 24th ed. Philadelphia, PA: Elsevier; 2022:chap 15.
Verbalis JG. Disorders of water balance. In: Yu ASL, Chertow GM, Luyckx VA, Marsden PA, Skorecki K, Taal MW, eds. Brenner and Rector's The Kidney. 11th ed. Philadelphia, PA: Elsevier; 2020:chap 15.
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
All rights reserved.