Urine specific gravity

Female urinary tract — The female and male urinary tracts are relatively the same except for the length of the urethra.

Also known as: Urine density

Definition

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

Normal values are between 1.020 to 1.028.

Note: Normal value ranges may vary slightly among different laboratories. 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)
Dehydration
Diarrhea that causes dehydration
Glucosuria
Heart failure (related to decreased blood flow to the kidneys)
Renal arterial stenosis
Shock
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
Renal failure
Renal tubular necrosis
Severe kidney infection (pyelonephritis)

Additional conditions under which the test may be performed:

Complicated UTI (pyelonephritis)
High blood sodium level
Low blood sodium level
Excessive urination

Special considerations

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.

References

Bazari H. Approach to the patient with renal disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007:chap 115.

Disease

Acute kidney failure

Acute (sudden) kidney failure is the sudden loss of the ability of the kidneys to remove waste and concentrate urine without losing .
Disease

Interstitial nephritis

Interstitial nephritis is a kidney disorder in which the spaces between the kidney tubules become swollen (inflamed). The inflammation can affect the kidneys’ function, including their ability to filter waste.
Test

Osmolality - blood

Osmality is a test that measures the concentration of all chemical particles found in the fluid part of blood.
Test

Urine concentration test

A urine concentration test measures the ability of the kidneys to conserve or excrete water appropriately. See also:
Disease

Pyelonephritis

Pyelonephritis is an infection of the kidney and the ureters, the ducts that carry urine away from the kidney.
Disease

Hepatorenal syndrome

Hepatorenal syndrome is a condition in which there is progressive kidney failure in a person with of the liver. It is a serious and often life-threatening complication of cirrhosis.
Disease

Diabetes insipidus - central

Central diabetes insipidus is a rare condition that involves extreme thirst and excessive urination. See also:
Test

Glucose test - urine

The glucose urine test measures the amount of sugar (glucose) in a urine sample. The presence of glucose in the urine is called glycosuria or glucosuria. See also:
Disease

Renal artery stenosis

Renal artery stenosis is a narrowing or blockage of the artery that supplies blood to the kidney. See also:
Disease

Diabetes insipidus - nephrogenic

Nephrogenic diabetes insipidus is a disorder in which a defect in the small tubes (tubules) in the kidneys causes a person to pass a large amount of urine. The tubules allow water to be removed from the body or reabsorbed. See also:
Disease

Hyponatremia

Hyponatremia is a metabolic condition in which there is not enough sodium (salt) in the body fluids outside the cells.
Disease

Heart failure

Heart failure, also called congestive heart failure, is a condition in which the heart can no longer pump enough blood to the rest of the body.
Disease

Acute tubular necrosis

Acute tubular necrosis is a kidney disorder involving damage to the tubule cells of the kidneys, resulting in .
Disease

Dehydration

Dehydration means your body does not have as much water and fluids as it should. Dehydration can be caused by losing too much fluid, not drinking enough water or fluids, or both. Vomiting and diarrhea are common causes. Infants and children are more susceptible to dehydration than adults because ...

Review date:: August 7, 2009
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.

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