Urine specific gravity test
Urine specific gravity is a laboratory test that shows the concentration of all chemical particles in the urine.
How the Test is Performed
After you provide a urine sample, it is tested right away. The health care provider uses a dipstick made with a color-sensitive pad. The color the dipstick changes to will tell the provider the specific gravity of your urine. The dipstick test gives only a rough result. For a more accurate result, your provider may send your urine sample to a lab.
How to Prepare for the Test
Your provider will ask you to temporarily stop taking any medicines that may affect the test results. These may include dextran and sucrose. Be sure to tell your provider about all the medicines you take. DO NOT stop taking any medicine before talking to your provider.
Also tell your provider if you recently received intravenous dye (contrast medium) for an x-ray. Contrast dye can also affect test results.
How the Test will Feel
The test involves only normal urination. There is no discomfort.
Why the Test is Performed
This test helps evaluate your body's water balance and urine concentration.
Osmolality is a more specific test for urine concentration. The urine specific gravity test is easier and more convenient, and is usually part of a routine urinalysis. The osmolality test may not be needed.
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 conditions such as:
- Loss of body fluids (dehydration)
- Diarrhea that causes dehydration
- Heart failure
- Sugar (glucose) in the urine
- Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
Decreased urine specific gravity may be due to:
- Damage to kidney tubule cells (renal tubular necrosis)
- Diabetes insipidus
- Drinking too much fluid
- Kidney failure
There are no risks with this test.
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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.