Urine specific gravity test

Definition

Urine specific gravity is a laboratory test that shows the concentration of all chemical particles in the urine.

Alternative Names

Urine density

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 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:

• Had any type of anesthesia for an operation.
• Received intravenous dye (contrast medium) for an imaging test, such as a CT or MRI scan.
• Used herbs or natural remedies, especially Chinese herbs.

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.

Normal Results

Urine 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 urine osmolality test may not be needed.

The normal range for urine specific gravity is 1.005 to 1.030. 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.

What Abnormal Results Mean

Increased urine specific gravity may be due to conditions such as:

• Adrenal glands do not produce enough hormones (Addison disease)
• Heart failure
• High sodium level in the blood
• Loss of body fluids (dehydration)
• Narrowing of the kidney artery (renal artery stenosis)
• Shock
• Sugar (glucose) in the urine
• Syndrome of inappropriate ADH 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
• Low sodium level in the blood
• Severe kidney infection (pyelonephritis)

Risks

There are no risks with this test.

References

Krishnan A, Levin A. Laboratory assessment of kidney disease: glomerular filtration rate, urinalysis, and proteinuria. 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 23.

Riley RS, McPherson RA. Basic examination of the urine. In: McPherson RA, Pincus MR, eds. Henry's Clinical Diagnosis and Management by Laboratory Methods. 23rd ed. St Louis, MO: Elsevier; 2017:chap 28.

Villeneuve P-M, Bagshaw SM. Assessment of urine biochemistry. In: Ronco C, Bellomo R, Kellum JA, Ricci Z, eds. Critical Care Nephrology. 3rd ed. Philadelphia, PA: Elsevier; 2019:chap 55.