Advocate Health Care
a patient or visitor a physician or healthcare professional an employer
PrintEmail
Decrease (-) Restore Default Increase (+) font size

medical services home
search by doctor name 
Doctor Name Contains (Smart Search)
OR
search by specialty

search by city/zip code
Find a doctor near your location by entering a city name OR ZIP code.
Near:


Within miles:
0 1 5 10 15 30 30+

search by insurance
Insurance Name Contains (Smart Search)
 (what's this)
 
related health information
 

Urine concentration test

Definition

A urine concentration test measures the ability of the kidneys to appropriately conserve or excrete water.

Alternative Names

Water loading test; Water deprivation test

How the Test is Performed

For this test, the specific gravity of urine, urine electrolytes, and/or urine osmolality are measured before and after one or more of the following:

  • Water loading -- drinking large amounts of water or receiving fluids through a vein
  • Water deprivation -- not drinking fluids for a certain amount of time
  • ADH administration -- receiving antidiuretic hormone (ADH), which should cause the urine to become concentrated

After you provide a urine sample, it is tested right away. For urine specific gravity, the health care provider uses a dipstick made with a color-sensitive pad. The color the dipstick changes to tells the provider the specific gravity of your urine. The dipstick test gives only a rough result. For a more accurate specific gravity result or measurement of urine electrolytes or osmolality, your health care provider will send your urine sample to a lab.

If needed, your health care provider may ask you to collect your urine at home over 24 hours. Your provider will tell you how to do this. Follow instructions exactly so that the results are accurate.

How to Prepare for the Test

Eat a normal, balanced diet for several days before the test. Your health care provider will give you instructions for water loading or water deprivation.

Your health care provider will ask you to temporarily stop any medicines that may affect the test results. Be sure to tell your provider about all the medicines you take, including dextran and sucrose. Do not stop taking any medicine before talking to your doctor.

Also tell your provider if you recently received intravenous dye (contrast medium) for an x-ray. The dye can also affect test results.

How the Test will Feel

The test involves only normal urination. There is no discomfort.

Why the Test is Performed

This test is most often done if your doctor suspects central diabetes insipidus. The test can help tell it apart from nephrogenic diabetes insipidus.

This test may also be done if you have signs of SIADH (syndrome of inappropriate ADH).

Normal Results

In general, normal values for specific gravity are as follows:

  • 1.000 to 1.030 (normal specific gravity)
  • 1.001 after drinking excessive amounts of water
  • More than 1.030 after avoiding fluids
  • Concentrated after receiving ADH

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your doctor about the meaning of your specific test results.

What Abnormal Results Mean

Increased urine concentration may be due to different conditions, such as:

  • Heart failure
  • Loss of body fluids (dehydration) from diarrhea or excessive sweating
  • Narrowing of the kidney artery (renal arterial stenosis)
  • Sugar, or glucose, in the urine
  • Syndrome of inappropriate antidiuretic hormone secretion (SIADH)
  • Vomiting

Decreased urine concentration may indicate:

  • Diabetes insipidus
  • Drinking too much fluid
  • Kidney failure (loss of ability to reabsorb water)
  • Severe kidney infection (pyelonephritis)

Risks

There are no risks with this test.

References

Gerber GS, Brendler CB. Evaluation of the urologic patient: history, physical examination, and urinalysis. In: Wein AJ, Kavoussi LR, Novick AC, et al., eds. Campbell-Walsh Urology. 10th ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 3.

McPherson RA, Ben-Ezra J. Basic examination of urine. In: McPherson RA, Pincus MR, eds. Henry’s Clinical Diagnosis and Management by Laboratory Methods. 22nd ed. Philadelphia, Pa: Elsevier Saunders; 2011:chap 28.


Review Date: 8/25/2013
Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Also reviewed by David Zieve, MD, MHA, Bethanne Black, and the A.D.A.M. Editorial team.
The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.
adam.com
 

quick links patient information health care professional information employer information connect with Advocate

About Advocate | Contact Us | Jobs | SiteMap | Terms of Use | Notice of privacy practices ®Advocate Health Care, Downers Grove, Illinois, USA | 1.800.3.ADVOCATE | TDD 312.528.5030