Urine concentration test

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Female urinary tract

Male urinary tract

Urine concentration test

A urine concentration test measures the ability of the kidneys to conserve or excrete water appropriately. (See also urine specific gravity.)

Water loading test; Water deprivation test

Collect a "clean-catch" (midstream) urine sample. To obtain a clean-catch sample, men or boys should clean the head of the penis. Women or girls need to wash the area between the lips of the vagina with soapy water and rinse well.

As you start to urinate, allow a small amount to fall into the toilet bowl to clear the urethra of contaminants. Then, put a clean container under your urine stream and catch 1 to 2 ounces of urine. Remove the container from the urine stream. Cap and mark the container and give it to the health care provider or assistant.

For infants, thoroughly wash the area around the urethra. Open a urine collection bag (a plastic bag with an adhesive paper on one end), and place it on the infant. For boys, the entire penis can be placed in the bag and the adhesive attached to the skin. For girls, the bag is placed over the labia. Diaper as usual over the secured bag.

This procedure may take a couple of attempts -- lively infants can displace the bag. The infant should be checked frequently and the bag changed after the infant has urinated into the bag. The urine is drained into the container for transport to the laboratory.

For this test, the specific gravity of urine is measured before and after water loading (urine should become dilute), water deprivation (urine should become concentrated), or administration of ADH (anti-diuretic hormone, which should cause the urine to become concentrated).

Water loading means you drink excessive amounts of water or you receive intravenous solutions. Water deprivation means you do not drink fluids for a period of time.

Eat a normal, balanced diet for several days before the test. Submit a urine sample to the laboratory. If contamination of the specimen (by vaginal discharge or bleeding) is likely, collect a clean-catch sample.