Urine Specific Gravity Test: What Is It, And What Do Results Mean?

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Medical News TodaySubscribeWhat is a urine-specific gravity test?

Medically reviewed by Mia Armstrong, MD — Written by Shannon Johnson — Updated on August 22, 2024

About the test
Results
Lowering specific gravity
Raising specific gravity
Definition
Procedure
Preparation
Summary

A urine-specific gravity test compares the density of urine with the density of water. The test may help healthcare professionals identify dehydration, a kidney problem, or a condition like diabetes insipidus.

The test shows the concentration of particles in urine. It involves collecting a urine sample for testing in a laboratory. Read on to learn more about the urine-specific gravity test and what the results may mean.

What is a urine-specific gravity test?

A urine-specific gravity test is a laboratory test that shows the total concentration of all types of chemical particles in the urine. It compares the density of water to the density of an equal volume of urine.

This test can be an important part of diagnosis because it can show the kidney’s ability to dilute or concentrate urine. Specific gravity tests may not be the most reliable laboratory tests. However, they can rapidly indicate the potential presence of renal disease.

This can show a healthcare professional that more tests may be required.

What do the results mean?

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Doctors consider the result of a urine-specific gravity test to be normal if it is within the range 1.003–1.030.

However, doctors cannot specify low, acceptable, or high values because many factors can affect urine composition. Urine-specific gravity is only one measure of health.

If a doctor identifies an unusual result, they may recommend further testing to determine if an underlying condition is causing the urine changes.

Additional urine testing may include:

urine culture
urine osmolality
urine pH
ketone testing

Results from these other tests will help make an accurate diagnosis.

Learn more about urinalysis.

Causes of high readings

High specific gravity suggests that the concentration of urine is too high. This can be a sign of dehydration, and a healthcare professional may recommend drinking more clear fluids.

Conditions that cause high specific gravity include:

dehydration
diarrhea or vomiting resulting in dehydration
congestive heart failure
shock

High levels of certain substances in the urine can also cause high specific gravity.

Substances include:

glucose
proteins
red or white blood cells

Learn more about red blood cells in the urine.

Causes of low readings

Low specific gravity suggests that urine is too diluted. The person may be drinking too much fluid or have a condition that makes them thirsty.

Diuretics can also cause urine to be more diluted. This is because they remove extra sodium from the blood and water follows.

Conditions that cause low specific gravity include:

diabetes insipidus
kidney damage or kidney failure
drinking too much fluid, for example, due to excess thirst, or polydipsia
using diuretics, or water pills, which cause the body to remove extra sodium from the urine
congestive heart failure

Hyponatremia can result from some of these conditions. If a person has hyponatremia, sodium levels in the body are too low.

Learn about the causes of high sodium levels in the body.

Other factors that can affect results

Other factors that may give an inaccurate result include:

exposing the sample to light and temperature, which can change the composition of some particles
bacterial growth
alkaline pH
glucose, which can affect pH
contrast agents used in scans and other procedures
recent exercise
some foods, such as beetroot, rhubarb, blackberries, and food colorings
some medications, including ibuprofen, chloroquine, and metronidazole

Learn more about the pH levels of urine.

Urine specific gravity and urine color

If a person has concerns about whether they are consuming enough fluid, checking their urine color may help. Urine tends to be darker and has higher specific gravity when a person does not drink enough fluids.

Urine is lighter and has lower specific gravity when a person is well-hydrated.

If a person continues to have dark urine after consuming extra fluid, it may be time to speak with a healthcare professional.

Urine-specific gravity tests can give a more precise measurement of the urine’s concentration than just looking at the color alone.

Learn more about what different colors of urine can mean.

How to lower urine specific gravity

If urine specific gravity is high due to dehydration, a healthcare professional may recommend:

drinking more clear fluids, especially water
consuming foods containing water, such as soups or jello
having IV fluids if the person is unable to take fluids by mouth

If urine-specific gravity is high for another reason, such as diarrhea or shock, the healthcare professional will investigate and treat the underlying cause.

Learn more about how to manage dehydration.

How to raise urine specific gravity

If urine specific gravity is low, a person may have a health condition that causes them to drink a lot of fluid or affects their kidney function.

A healthcare professional may:

ask the person about any other symptoms
ask if they have been drinking large amounts of fluid
suggest further tests to identify the cause of the problem

A person does not need to think about raising their urine specific gravity. A healthcare professional would need to find and correct the underlying cause. Addressing the cause can help normalize the specific gravity.

Learn more about what happens if you drink too much fluid.

What does urine-specific gravity mean?

Urine contains solutes, or soluble particles. If it did not contain these particles, urine specific gravity would be 1.000, the same as water. Urine-specific gravity measures how many particles are in a person’s urine compared with water.

The higher the number of particles in the urine, the higher the urine specific gravity.

If there are more particles than in water, urine will be denser, and the specific gravity will be higher. Particles present in the urine may include glucose (sugar), proteins, and ketones.

Urine-specific gravity procedure

The test should not be uncomfortable and is usually brief. The healthcare professional might request multiple urine-specific gravity tests in one day to see how well the kidneys compensate for a possible problem.

The healthcare professional may ask the person to collect a “clean catch” specimen to prevent contaminating the sample with bacteria from the skin.

To collect a clean catch specimen, a person should:

Wash their hands and have the container ready for use, taking care to touch only the outside.
Clean the urethral area.
Begin urinating, then hold the container under the stream.
Collect at least 1 ounce (oz), or 30 milliliters (ml), of urine, as shown on the side of the container.
Replace the cover securely, touching only the outside of the container.
Wash hands thoroughly and follow any instructions for delivering the pot to the doctor or a lab for testing.

A laboratory technician performs the test using a refractometer, which projects light into the sample and helps determine the density of the urine.

Learn more about the kidneys and how they work.

Preparing for the test

Preparation for a urine-specific gravity test is typically straightforward.

Before the test, the healthcare professional may ask the person to stop taking certain medications or to avoid some foods, such as beets and rhubarb, as these may affect the results.

People should also let their healthcare professionals know if they have recently received intravenous contrast dye for a medical test.

Learn more about how foods and medications can affect urine.

Summary

A urine-specific gravity test is a straightforward test that looks at a person’s urine concentration. The person will need to collect a clean urine sample for testing in a laboratory.

Urine concentration can show how well the kidneys are functioning or indicate an underlying condition that is altering the body’s fluid status.

A urine-specific gravity test cannot diagnose a condition, but it can play a role in identifying underlying health conditions ranging from kidney failure to dehydration.

Diabetes
Medical Devices / Diagnostics
Urology / Nephrology
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How we reviewed this article:

SourcesMedical News Today has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical journals and associations. We only use quality, credible sources to ensure content accuracy and integrity. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

Clean catch urine collection guidelines for males and females. (2022).https://www.nationwidechildrens.org/family-resources-education/health-wellness-and-safety-resources/helping-hands/clean-catch-urine-collection-guidelines-for-males-and-females
Dehydration. (2022).https://www.nhs.uk/conditions/dehydration/
Gounden V, et al. (2023). Renal function tests.https://www.ncbi.nlm.nih.gov/books/NBK507821/
Hyponatremia. (2023).https://www.kidney.org/atoz/content/hyponatremia
Queremel Milani, D A, et al. (2023). Urinalysis.https://www.ncbi.nlm.nih.gov/books/NBK557685/
Water density. (2018).https://www.usgs.gov/special-topics/water-science-school/science/water-density

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Medically reviewed by Mia Armstrong, MD — Written by Shannon Johnson — Updated on August 22, 2024

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Urine Specific Gravity Test: What Is It, And What Do Results Mean?

What is a urine-specific gravity test?

What do the results mean?

Causes of high readings

Causes of low readings

Other factors that can affect results

Urine specific gravity and urine color

How to lower urine specific gravity

How to raise urine specific gravity

What does urine-specific gravity mean?

Urine-specific gravity procedure

Preparing for the test

Summary

How we reviewed this article:

Latest news

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