Specific Gravity of Urine

What is specific gravity of urine in the kidneys?

Specific gravity of urine is a fast, simple urinalysis test that measures how well your kidneys balance water and remove chemical particles (waste products) from your blood — it evaluates the density of your urine (pee) relative to the density of water. Waste products in your pee may include:

• Urea. Your body produces urea when it breaks down protein in foods you eat.
• Uric acid. Your body produces uric acid when it breaks down purines. Purines are natural chemicals that are common in meats, beer and liquor.
• Salts (sodium). Salts are common in many foods, and it’s even present in some medicines. It helps balance other minerals in your blood and carry nutrients throughout your body.
• Amino acids. These are the building blocks of protein.

A low specific gravity is when you have more water in your pee (overly hydrated or diluted pee). A high specific gravity is when you have a lot of waste products in it (dehydrated or concentrated pee). Sometimes, your specific gravity is abnormal because you’re drinking too many fluids or not enough. But sometimes, a condition that affects your kidneys can impact your specific gravity.

Specific gravity of urine has many different names. These include:

• Urine concentration test
• Urinary specific gravity
• Urine S.G
• S.G. urine test
• Specific gravity urinalysis
• Urine-specific gravity test
• Urine density
• Water loading test
• Water deprivation test

What does specific gravity of urine indicate?

Specific gravity of urine shows the concentration of all chemical particles in your pee. If you have dilute pee, the causes may include:

• Drinking too many fluids (overhydration)
• Your body doesn’t make enough vasopressin (antidiuretic hormone or ADH) or your kidneys don’t respond to it properly (diabetes insipidus)
• Kidney infection (pyelonephritis)
• Chronic kidney disease (CKD)
• Kidney failure

If you have concentrated pee, the causes may include:

• Dehydration
• Throwing up (vomiting)
• Loose, watery poop (diarrhea)
• Your body makes too much antidiuretic hormone (syndrome of inappropriate antidiuretic hormone secretion or SIADH)
• Not enough blood flows through your kidneys (prerenal azotemia)
• Your adrenal glands don’t make enough hormones (Addison’s disease)

When is specific gravity of urine performed?

A healthcare provider may recommend a urine-specific gravity test if they suspect you have a condition that affects your kidneys’ ability to balance water or remove wastes from your blood.

How does specific gravity of urine work?

You provide a urine sample — that is, you pee in a cup — and a healthcare provider will insert a dipstick into your sample. A dipstick is a thin strip of plastic or paper with patches of chemicals. The chemicals change color according to the specific gravity of your pee.

In some cases, a provider may insert a few drops of your urine sample into a refractometer. A refractometer is a medical device that shows how much light passes through pee. It’s more accurate than a dipstick. If you have a lot of water in your pee, more light passes through your urine sample. If you have more waste products in your pee, less light will pass.

What to expect before a specific gravity of urine test?

A healthcare provider will review your medical history and ask you questions. Be sure to tell them about all prescription and over-the-counter medications you’re taking, including herbal supplements. In some cases, you may need to stop taking certain medications shortly before the test because they may affect your results. Don’t stop taking any medications unless a provider specifically says you should.

You should also let a provider know if you’ve had any recent imaging tests or procedures that require anesthesia. Anesthesia and imaging tests that use contrast dyes, such as an MRI or CT scan, can affect your urine gravity.

A provider will call you ahead of your test with precise directions. You may need to limit how much fluid you drink for at least 12 hours before a specific gravity of urine test.

What to expect during specific gravity of urine?

You’ll usually provide a urine sample at a healthcare provider’s office or lab. It’s important to wash your hands with soap and water before you pee in the cup.

Let your provider know if you have difficulty peeing away from home (shy bladder syndrome). They may give you a cup you can take home or suggest another option that’s more comfortable for you. You should also let them know if you’re getting your period (menstruating). Menstrual blood can affect your specific gravity of urine.

Your provider will tell you what to do with your sample once you finish. You may hand it to another provider or leave it in a collection cupboard.

What to expect after specific gravity of urine?

After you provide your urine sample, a healthcare provider will immediately run a dipstick test or send it to a lab to examine with a refractometer.

What type of results do you get and what do the results mean?

The expected or normal range for urine-specific gravity is 1.0101 to 1.030. Water’s specific gravity is 1.

If your urine-specific gravity is lower than 1.0101, that means your pee has more water in it.

If your urine-specific gravity is higher than 1.030, that means there are more waste products in your pee.

When should I know the results of specific gravity of urine?

Your healthcare provider will get your specific gravity of urine right away if they use a dipstick. If they use a refractometer, it may take longer.

A urine-specific gravity test is usually one part of many different urine tests. So, you’ll likely get the results of all your tests in one to two business days. A provider may call you with the results or they may send them to you electronically.

If the results are abnormal, what are the next steps?

If you have abnormal specific gravity of urine, your healthcare provider may recommend additional tests to help diagnose the cause. The tests may depend on whether you’re overly hydrated or dehydrated. But they may include:

• Blood tests, including an osmolality blood test, comprehensive metabolic panel and blood urea nitrogen (BUN) test
• Imaging tests, including an MRI, CT scan or kidney (renal) ultrasound
• Additional urine testing

When should I call my healthcare provider?

Call your healthcare provider if you:

• Don’t get your results within a few days
• Notice urine changes
• Have any questions about your results