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What Is Urine Specific Gravity?

Reviewed by Dan Brennan, MD on April 27, 2021

‌A urine concentration test provides the specific gravity of your urine. This measures your kidneys’ ability to balance water content and excrete waste. It is important in diagnosing some health conditions that impact water content in your urine.

Understanding Urine Specific Gravity

A urine concentration test is also called a water loading test or a water deprivation test. The specific gravity of urine refers to the electrolytes and urine osmolality. Depending on your doctor’s concerns, they give you specific instructions for eating, drinking, and taking medication prior to the test. These may include:

  • Drink water – Your doctor may ask you to drink more water than usual or hook you up to receive fluids via an IV prior to the test.
  • Don’t drink water – You may need to stop drinking fluids of any kind for a specified amount of time leading up to your test.‌
  • Antidiuretic hormone (ADH) – This is a medication that may help to concentrate your urine.

How Urine Specific Gravity Tests Work

First, you provide a urine sample that is tested immediately. Your doctor or nurse takes a dipstick that uses a color-sensitive pad to provide results. The dipstick reacts to your urine, changing colors based on the specific gravity of your urine.

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This gives your doctor an idea of whether your urine is too concentrated or not concentrated enough. For more specific results, the sample is assessed by a lab. Then you’ll know what levels of electrolytes and osmolality your urine has.

In some cases, your doctor may ask that you take samples of urine from home over a 24-hour period. No matter how the test is conducted, make sure you follow your doctor’s instructions carefully. Let them know if you ate or drank something outside of the guidelines that may impact your results.

Preparing for Your Test

Eat as you usually would for several days leading up to the test. Don’t make any changes to your diet outside of suggestions from your doctor. They may ask you to stop taking certain medications prior to the urine test, so tell your doctor about any medications you’re taking. This includes over-the-counter medications and prescriptions.

If your doctor doesn’t have concerns about your medications, continue taking them as normal. Other factors that may impact your urine specific gravity test are dyes used for CT and MRI scans. If you have any other tests conducted, let your doctor know about each one.

Impact of Urine Specific Gravity on Your Health

A urine specific gravity test is used to test for diagnosing many health conditions, primarily central diabetes insipidus and nephrogenic diabetes insipidus. Both health conditions cause your body to signal excessive thirst, resulting in more urination.

However, the cause of each condition is different. Damage to the pituitary gland or hypothalamus causes primary central diabetes. A malformation of your kidneys contributes to nephrogenic diabetes insipidus.

Your urine’s specific gravity isn’t explicitly bad for your health. The results do signal other health conditions that may harm your health. The normal specific gravity ranges from person to person. Your urine specific gravity is generally considered normal in the ranges of 1.005 to 1.030.

If you drink a lot of water, 1.001 may be normal. If you avoid drinking fluids, levels higher than 1.030 may be normal. Your doctor takes your specific symptoms, eating habits, and drinking habits into consideration when assessing your results.

Signs that your urine specific gravity is off. Both of these health conditions impact the amount of sodium and potassium in your blood, also called electrolytes. Signs that you may have an electrolyte imbalance include:

  • Feeling weak
  • Nausea or vomiting
  • Lack of appetite
  • Having muscle cramps ‌
  • Feeling confused

Risks of Urine Specific Gravity

Health conditions that contribute to an imbalance of fluids in your urine include:

  • Heart failure
  • Kidney failure
  • Kidney infection
  • Dehydration because of excessive sweating
  • Diarrhea or vomiting
  • Renal arterial stenosis, or the narrowing of your kidney’s artery
  • Sugar in your urine
  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
  • Diabetes insipidus‌
  • Drinking more fluids than your body needs

If any health conditions go untreated, they may lead to permanent damage or loss of life. Talk to your doctor about any concerns you have and share your symptoms. While some health conditions are not preventable, they are treatable. Early intervention is the key to maintaining your quality of life.

WebMD Medical Reference

Sources

SOURCES:

Mayo Clinic: “Diabetes insipidus.”

Mount Sinai: “Osmolality urine test.”

University of California San Francisco: “Urine Specific Gravity Test.”

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