Urine specific gravity test
Urine specific gravity
Urine specific gravity is a laboratory test that measures the concentration of all chemical particles in the urine.
How the test is performed
The test requires a clean-catch urine sample. For information on how to collect this urine sample, see: Clean-catch urine culture
How to prepare for the test
Your health care provider will instruct you, if necessary, to discontinue drugs that may interfere with the test. Drugs that can increase specific gravity measurements include dextran and sucrose. Receiving intravenous dye (contrast medium) for an x-ray exam up to 3 days before the test can also interfere with results.
Eat a normal, balanced diet for several days before the test.
How the test will feel
The test involves only normal urination, and there is no discomfort.
Why the test is performed
This test helps evaluate your body's water balance and urine concentration.
Normal values are between 1.000 to 1.030.
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 results.
What abnormal results mean
Increased urine specific gravity may be due to:
- Addison's disease (rare)
- Diarrhea that causes dehydration
- Heart failure (related to decreased blood flow to the kidneys)
- Renal arterial stenosis
- Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Decreased urine specific gravity may be due to:
- Aldosteronism (very rare)
- Excessive fluid intake
- Diabetes insipidus - central
- Diabetes insipidus - nephrogenic
- Kidney failure
- Renal tubular necrosis
- Severe kidney infection (pyelonephritis)
Additional conditions under which the test may be performed:
- Complicated UTI (pyelonephritis)
- High blood sodium level (hypernatremia)
- Low blood sodium level (hyponatremia)
- Excessive urination
Osmolality is a more specific test for urine concentration. However, the specific gravity measurement is easier and more convenient and usually part of a routine urinalysis. It frequently makes the osmolality measurement unnecessary.
Landry DW, Bazari H. Approach to the patient with renal disease. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 116.
Reviewed by:David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.
A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC'saccreditation program is an independent audit to verify that A.D.A.M. follows rigorousstandards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information andservices. Learn more about A.D.A.M.'s editorialpolicy, editorialprocess, and privacypolicy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch.)
The information provided herein should not be used during any medical emergency or for the diagnosis or treatmentof any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions.Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 2014 A.D.A.M., Inc. Any duplication ordistribution of the information contained herein is strictly prohibited.