What is a urine specific gravity test

Conditions that cause high specific gravity include:

Urine Specific Gravity Test

A urine test is a painless way for your healthcare provider to check your health and test for abnormalities. One thing your healthcare provider may check for in your urine sample test, or urinalysis, is specific gravity.

A urine specific gravity test compares the density of urine to the density of water. This quick test can help determine how well your kidneys are diluting your urine.

Urine that’s too concentrated could mean that your kidneys aren’t functioning properly or that you aren’t drinking enough water.

Urine that isn’t concentrated enough can mean you have a rare condition called diabetes insipidus, which causes thirst and the excretion of large amounts of diluted urine.

The main role of your kidneys is to filter your blood and maintain normal electrolyte balance. Testing urine specific gravity is a quick way for your healthcare provider to tell if your kidneys are trying to compensate for some abnormality.

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Specific gravity testing is useful if your healthcare provider thinks you have any of the following conditions:

• dehydration or overhydration
• heart failure
• shock
• diabetes insipidus
• kidney failure
• kidney infection
• urinary tract infection
• hyponatremia, or low sodium levels
• hypernatremia, or elevated sodium levels

You may have to take a urine specific gravity test several times in one day. This will help your healthcare provider to see how well your kidneys are compensating.

Before you take a urine specific gravity test, your healthcare provider may ask you to do a few things to prepare for it. First, they’ll ask you to stop taking any medications that could interfere with the test results, such as those containing sucrose or dextran.

You’ll likely need to wait to take the test if you’ve recently been given intravenous contrast dye for an X-ray or MRI scan. If it’s been more than three days since the dye was administered, it should be fine for you to take the urine test.

You should also eat a balanced diet in the days leading up to the test. This diet should exclude certain foods that can affect the color of your urine. These include:

• beets
• blackberries
• carrots
• fava beans
• rhubarb

A sample for a urine specific gravity test contains at least 1 to 2 ounces of urine. The best time to get a sample is first thing in the morning, when your urine is the most concentrated.

Your healthcare provider will give you a cup to collect a urine sample.

For the best sample, you should use an antibacterial wipe to clean the area around your urethra. This will reduce the likelihood that bacteria will contaminate the sample.

Urinate a small amount, and then place the cup under your urine stream. Urinate into the cup until you have a large enough sample, and then finish urinating into the toilet. This is known as the clean-catch (or midstream) method.

Your healthcare provider will send the urine sample to a laboratory while it’s fresh. This will ensure the best results.

A lab technician will use a refractometer to project light into the sample and determine its density. This is more reliable than the dipstick method, in which a stick is placed in the urine to measure how much it sinks or floats.

While there are home tests, the results won’t be as accurate as those conducted by a professional in a sterile environment. Home tests are more susceptible to contamination.

Another benefit to taking the test at your healthcare provider’s office is that they can send the sample to the lab for more detailed testing and analysis.

Osmolality tests are sometimes used to evaluate how the kidneys dilute and concentrate urine, with osmolality being the index of a concentration. Knowing the osmolality of your urine can help your healthcare provider diagnose certain conditions.

To understand urine concentrations, think about the dark color of your urine when you haven’t had anything to drink in some time. Your urine is lighter and usually has lower specific gravity when you’re well-hydrated.

Urine specific gravity is a more precise measurement of your urine’s overall concentration than looking at the color of your urine alone.

Your healthcare provider will look at the ratio of the density of your urine to the density of water. To put it another way, the specific density of water would be 1.000. Ideally, urine specific gravity results will fall between 1.002 and 1.030 if your kidneys are functioning normally.

Specific gravity results above 1.010 can indicate mild dehydration. The higher the number, the more dehydrated you may be.

High urine specific gravity can indicate that you have extra substances in your urine, such as:

Your healthcare provider will use the results from your urine specific gravity test, along with other urinalysis results, to come up with a diagnosis. Abnormal specific gravity results could indicate:

• excess substances in the blood
• kidney disease (high or low specific gravity can indicate an inability of the kidney tubules to function correctly)
• infection, such as a urinary tract infection
• brain injuries, which can cause a person to develop diabetes insipidus

A urinalysis can also measure the concentration of various cells. White blood cells can indicate an infection. And glucose can point to glucose intolerance or diabetes.

Other types of urine tests include urine pH tests, hemoglobin tests, and ketone tests. The results from these tests can help your healthcare provider make a more accurate diagnosis.

The urine specific gravity test involves urinating normally and isn’t associated with any harmful side effects. However, if you have a urinary tract infection, urinating may cause a burning or painful sensation.

Always notify your healthcare provider if you experience discomfort urinating or any unexpected symptoms.

A urine specific gravity test is a painless and easy test to take. Preparation is simple, and it only requires excluding a few things from your diet and temporarily stopping certain medications.

This test can help healthcare providers with a differential diagnosis. When used along with blood work or other urinalysis tests, it can also help healthcare providers identify different conditions.

In some cases, the urine specific gravity test will show that you’re dehydrated or overhydrated. If you’re extremely dehydrated and having trouble getting enough fluids, you may be given intravenous fluids to help hydrate you faster.

Mild dehydration can be resolved by consistently drinking more water. If you’re overhydrated, your healthcare provider may run more tests to look for metabolic disorders or liver, heart, brain, or kidney conditions that could be causing it.

Last medically reviewed on August 7, 2018

How we reviewed this article:

Healthline has strict sourcing guidelines and relies on peer-reviewed studies, academic research institutions, and medical associations. We avoid using tertiary references. You can learn more about how we ensure our content is accurate and current by reading our editorial policy.

• Capatina C, et al. (2015). Diabetes insipidus after traumatic brain injury. DOI:
  10.3390/jcm4071448
• Mayo Clinic Staff. (2017). Diabetes insipidus.
  mayoclinic.org/diseases-conditions/diabetes-insipidus/symptoms-causes/syc-20351269
• Mayo Clinic Staff. (2017). Urinalysis.
  mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907
• Test ID: UOSMU — osmolality, urine. (n.d.).
  mayomedicallaboratories.com/test-catalog/Clinical+and+Interpretive/9260
• Urinalysis. (2016).
  labtestsonline.org/tests/urinalysis
• Urinalysis. (n.d.).
  library.med.utah.edu/WebPath/TUTORIAL/URINE/URINE.html

What is a urine specific gravity test?

A urine-specific gravity test compares the density of urine with the density of water. This helps 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.

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.

Causes of high readings

High specific gravity suggests that the concentration of urine is too high. This can be a sign of dehydration, and the doctor 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.

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.

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.

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

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 doctor.

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

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

• drinking more clear fluids, especially water
• consuming foods containing water, such as soups or jello
• having intravenous 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 doctor will investigate and treat the underlying cause.

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.

• 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 doctor would need to find and correct the underlying cause. Addressing the cause can help normalize the specific gravity.

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, proteins, and ketones.

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

The doctor 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:

1. Wash their hands and have the container ready for use, taking care to touch only the outside.
2. Clean the urethral area.
3. Begin urinating, then hold the container under the stream.
4. Collect at least 1 ounce (oz), or 30 milliliters (ml), of urine, as shown on the side of the container.
5. Replace the cover securely, touching only the outside of the pot.
6. Wash the 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.

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

Before the test, the doctor 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 doctor know if they have recently received intravenous contrast dye for a medical test.

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.

Last medically reviewed on January 4, 2022

• Diabetes
• Medical Devices / Diagnostics
• Urology / Nephrology
• Cat 1
• urinaryhealth

How we reviewed this article:

Medical News Today has strict sourcing guidelines and draws only from peer-reviewed studies, academic research institutions, and medical journals and associations. We avoid using tertiary references. We link primary sources — including studies, scientific references, and statistics — within each article and also list them in the resources section at the bottom of our articles. 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. (2021).
  https://www.nationwidechildrens.org/family-resources-education/health-wellness-and-safety-resources/helping-hands/clean-catch-urine-collection-guidelines-for-males-and-females
• Dehydration. (2019).
  https://www.nhs.uk/conditions/dehydration/
• Gounden, V., et al. (2021). Renal function tests.
  https://www.ncbi.nlm.nih.gov/books/NBK507821/
• Hyponatremia. (2017).
  https://www.kidney.org/atoz/content/hyponatremia
• Queremel Milani, D. A., et al. (2021). 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 Carissa Stephens, RN, CCRN, CPN
Medically reviewed by Debra Rose Wilson, Ph.D., MSN, R.N., IBCLC, AHN-BC, CHT
Medically reviewed by Maria S. Prelipcean, MD
Medically reviewed by Debra Sullivan, Ph.D., MSN, R.N., CNE, COI

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© 2004-2023 Healthline Media UK Ltd, Brighton, UK, a Red Ventures Company. All rights reserved. MNT is the registered trade mark of Healthline Media. Any medical information published on this website is not intended as a substitute for informed medical advice and you should not take any action before consulting with a healthcare professional. See additional information.