The osmolality urine test measures the concentration of particles in urine.
Osmolality can also be measured using a blood test.
A clean-catch urine sample is needed. The clean-catch method is used to prevent germs from the penis or vagina from getting into a urine sample. To collect your urine, the health care provider may give you a special clean-catch kit that contains a cleansing solution and sterile wipes. Follow instructions exactly.
Your health care provider may tell you that you need to limit your fluid intake 12 to 14 hours before the test.
Your provider will ask you to temporarily stop taking any medicines that may affect the test results. Be sure to tell your provider about all the medicines you take, including dextran and sucrose. DO NOT stop taking any medicine before talking to your provider.
Other things can also affect the test results. Tell your provider if you recently:
The test involves normal urination. There is no discomfort.
This test helps check your body's water balance and urine concentration.
Osmolality is a more exact measurement of urine concentration than the urine specific gravity test.
Normal values are as follows:
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 results.
Abnormal results are indicated as follows:
Higher than normal measurements may indicate:
Lower than normal measurements may indicate:
There are no risks with this test.
Chernecky CC, Berger BJ. Osmolality - urine. In: Chernecky CC, Berger BJ, eds. Laboratory Tests and Diagnostic Procedures. 6th ed. St Louis, MO: Elsevier; Saunders; 2013:833-834.
Inker LA, Fan L, Levey AS. Assessment of renal function. In: Johnson RJ, Feehally J, Floege J, eds. Comprehensive Clinical Nephrology. 5th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 3.BACK TO TOP
Review Date: 7/15/2017
Reviewed By: Laura J. Martin, MD, MPH, ABIM Board Certified in Internal Medicine and Hospice and Palliative Medicine, Atlanta, GA. Also reviewed by David Zieve, MD, MHA, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.
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