Urine Specific Gravity Biomarker Testing
It shows how concentrated your urine is and how well your kidneys conserve water, with easy ordering and Quest-based lab results via Vitals Vault.
With Vitals Vault, you have access to a comprehensive range of biomarker tests.
Urine specific gravity is a simple measurement that tells you how concentrated your urine is. In everyday terms, it reflects the balance between how much water you are taking in and how much your kidneys are holding onto.
Because it can change quickly with hydration, exercise, illness, and medications, a single result is best read as a snapshot. When you pair it with your symptoms and other urine or blood tests, it can help you and your clinician understand whether your body is conserving water appropriately.
This test is often reported as part of a urinalysis, but it can also be ordered on its own when you need a focused look at urine concentration.
Do I need a Urine Specific Gravity test?
You might consider a urine specific gravity test if you are trying to make sense of symptoms that could relate to hydration or fluid balance, such as unusual thirst, frequent urination, lightheadedness, dry mouth, or dark urine. It can also be useful if you have been sick with vomiting or diarrhea, are training hard, or are adjusting diuretics (“water pills”), because all of those can shift urine concentration.
This test is also commonly used when a routine urinalysis shows something unexpected (for example, protein, blood, or glucose) and your clinician wants to know whether the urine sample was very dilute or very concentrated at the time. That context matters because concentration can make some urine findings look more pronounced.
If you have known kidney disease, recurrent kidney stones, diabetes, or a history of electrolyte problems, urine specific gravity can be one small but helpful piece of monitoring. It does not diagnose a condition by itself, but it can point to patterns that deserve follow-up.
If your result is out of range, the next step is usually to repeat the test under more controlled conditions and add companion labs (such as urine osmolality, serum electrolytes, and kidney function tests) so decisions are based on a full clinical picture.
Urine specific gravity is measured on a CLIA-certified laboratory urinalysis platform; results are educational and should be interpreted with a clinician, not used as a standalone diagnosis.
Lab testing
Order urine specific gravity (alone or as part of a urinalysis) through Vitals Vault.
Schedule online, results typically within about a week
Clear reporting and optional clinician context
HSA/FSA eligible where applicable
Get this test with Vitals Vault
Vitals Vault lets you order urine specific gravity testing directly, without needing to schedule a separate doctor visit just to get the lab started. You choose the test, complete checkout, and then visit a participating lab location for specimen collection.
Once your results are ready, you can use PocketMD to review what “low,” “in range,” or “high” can mean in your situation and what follow-up questions to bring to your clinician. This is especially helpful for urine tests, where timing, hydration, and medications can change the interpretation.
If your result looks inconsistent with how you feel, you can also use Vitals Vault to retest at a more appropriate time (for example, a first-morning sample) or add related labs so you are not guessing based on one number.
- Order online and test at a participating lab location
- PocketMD helps you prepare next steps and follow-up questions
- Easy retesting to confirm patterns when hydration changes day to day
Key benefits of Urine Specific Gravity testing
- Shows how concentrated your urine is at the moment of testing, which reflects recent fluid balance.
- Adds context to other urinalysis findings by clarifying whether the sample was dilute or concentrated.
- Helps you spot dehydration patterns that may not be obvious from thirst alone.
- Can support evaluation of frequent urination or excessive thirst when paired with glucose and electrolyte testing.
- Offers a simple way to track how your kidneys respond to illness, heat exposure, or endurance exercise.
- Helps monitor the impact of medications that change fluid handling, such as diuretics.
- Makes it easier to plan a smart retest (timing and hydration) and discuss results in PocketMD before you meet your clinician.
What is Urine Specific Gravity?
Urine specific gravity (USG) compares the density of your urine to the density of water. Water has a specific gravity of 1.000, and urine is usually higher because it contains dissolved particles such as electrolytes, urea, and other waste products.
Your kidneys continuously adjust how much water they excrete versus conserve. When you are dehydrated or losing fluid, your body releases antidiuretic hormone (ADH, also called vasopressin), and your kidneys conserve water, producing more concentrated urine and a higher specific gravity. When you are well hydrated, your kidneys excrete more water, producing more dilute urine and a lower specific gravity.
USG is not the same as urine osmolality. Osmolality measures the number of particles in urine more directly, while specific gravity is influenced by both particle number and particle size. That is why USG is best used as a practical screening tool and interpreted alongside your clinical context and other labs.
What a typical reference range looks like
Many labs report a typical adult range around 1.005 to 1.030, but the exact reference interval can vary. A value can be “normal” yet still not match what you would expect for your hydration status at that time, so the story around the sample matters.
Why timing and collection matter
A first-morning urine sample is often more concentrated because you have not been drinking overnight. A random daytime sample can be much more variable depending on how recently you drank fluids, exercised, or took certain medications.
What do my Urine Specific Gravity results mean?
Low urine specific gravity
A low urine specific gravity usually means your urine is dilute, which can happen after you drink a lot of fluids or receive IV fluids. If it stays low when you would expect your kidneys to concentrate urine (for example, with dehydration or overnight fasting), it can suggest impaired concentrating ability or hormone-related issues that affect water balance. Your clinician may consider follow-up tests such as urine osmolality, serum sodium, and kidney function labs to clarify the cause.
In-range (expected) urine specific gravity
An in-range result generally means your urine concentration is appropriate for the circumstances of collection. If you were well hydrated, a lower-in-range value may be expected, while a first-morning sample often trends higher. If you have symptoms like excessive thirst or frequent urination despite an in-range value, it may still be worth checking companion labs because USG is only one piece of fluid-balance assessment.
High urine specific gravity
A high urine specific gravity usually means your urine is concentrated, which commonly happens with dehydration, sweating, fever, vomiting, or diarrhea. It can also rise when there are more dissolved substances in the urine, such as glucose or protein, so a high value should be read alongside the rest of the urinalysis. If you are consistently high despite adequate fluid intake, your clinician may look for contributing conditions and confirm with urine osmolality and blood tests.
Factors that influence urine specific gravity
Hydration status is the biggest driver, but timing (first morning vs. random), recent exercise, heat exposure, and acute illness can shift results quickly. Medications such as diuretics and some kidney-active drugs can change urine concentration, and IV fluids can lower USG. Substances in urine—especially glucose and protein—can raise specific gravity, which is one reason it is helpful to review USG together with urine glucose, protein, and ketones when available.
What’s included
Frequently Asked Questions
What is a normal urine specific gravity range?
Many labs list a typical adult reference range around 1.005–1.030, but ranges can vary by lab and method. The more important question is whether the value makes sense for your hydration and the timing of the sample (for example, first morning vs. after drinking water).
Do I need to fast for a urine specific gravity test?
Fasting is not usually required. However, if your clinician wants a more standardized assessment, they may recommend a first-morning urine sample or specific instructions about fluid intake beforehand, because drinking a lot of water right before testing can lower the result.
What does low urine specific gravity mean?
Low USG usually means dilute urine, often from high fluid intake or IV fluids. If it remains low when you would expect concentration (such as after overnight fasting or during dehydration), it can suggest a problem with kidney concentrating ability or water-balance regulation, which should be evaluated with additional labs.
What does high urine specific gravity mean?
High USG usually means concentrated urine, most commonly from dehydration, sweating, fever, vomiting, or diarrhea. It can also be higher when urine contains more dissolved substances like glucose or protein, so it is best interpreted alongside the rest of your urinalysis.
How is urine specific gravity different from urine osmolality?
Specific gravity compares urine density to water and can be influenced by both the number and size of particles in urine. Osmolality measures particle concentration more directly. If results are confusing or you need a more precise assessment of concentrating ability, your clinician may order urine osmolality.
When should I retest urine specific gravity?
Retesting can be helpful if your result was out of range during unusual circumstances (heavy exercise, acute illness, or very high fluid intake). A common approach is to repeat with a first-morning sample or after following your clinician’s hydration instructions, and to add companion tests if symptoms persist.