Specific Gravity 

Updated: Feb 12, 2014
  • Author: Rugheed Ghadban, MD; Chief Editor: Eric B Staros, MD  more...
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Reference Range

Urinary specific gravity (SG) is a measure of the concentration of solutes in the urine. It measures the ratio of urine density compared with water density and provides information on the kidney’s ability to concentrate urine. A urinary specific gravity measurement is a routine part of urinalysis. [1, 2, 3] The reference range is 1.005-1.030. [3]

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Interpretation

Conditions associated with a high urine specific gravity include the following [1, 4] :

Conditions associated with a low urine specific gravity include the following [1, 4] :

  • Renal failure
  • Pyelonephritis
  • Glomerulonephritis
  • Psychogenic polydipsia
  • Increased intracranial pressure increases
  • Malignant hypertension
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Collection and Panels

Specifics for collection and panels are as follows [1, 4] :

  • Specimen type: Urine
  • Container: Plastic urine specimen container
  • Collection method: Random urine sample
  • Specimen volume: 20 mL
  • Panels: Urinalysis
  • Other instructions: Keep specimen cool; high temperatures alter the result
  • Related tests: Urine osmolality
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Background

Description

Urinary specific gravity is a measure of the concentration of solutes in the urine and provides information on the kidney’s ability to concentrate urine. Urine osmolality is a more specific test for urine concentration; however, urine specific gravity measurement is a routine part of urinalysis.

Indications/Applications

Indications for testing urine specific gravity include the following:

  • Complicated urinary tract infection (eg, pyelonephritis)
  • Hypernatremia
  • Hyponatremia
  • Polyuria

Considerations  [4]

The following may increase urine specific gravity and should be discontinued before testing:

  • Dextran
  • Sucrose
  • Intravenous contrast dye
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