WATER DEPRIVATION TEST

What is water deprivation test?
Outline of the procedure
After the test
Who will get the results?
General Matters


What is a water deprivation test?

This test is performed to check the regulation of fluid balance and and concentration power of your kidneys.

Regulation of the fluid balance is a complex process which involves the pituitary hormone called antidiuretic hormone (ADH), the response of the kidneys to ADH, amount of fluid intake, various salts content of your body, surrounding temperature, etc.

This test can be done only under medical supervision as it can potentially cause dehydration, fluid and salt imbalance.

OUTLINE OF THE PROCEDURE

Your named nurse will introduce herself and explain what to expect.

A small needle/canula will be inserted into a vein in the back of your hand or arm. This is called a venflon and allows your named nurse to obtain blood samples without causing too much discomfort.

This test involves initial measurement of blood and urine concentration at 0900 a.m. after fasting from mid-night.

You will then be allowed dry food only without any fluid up until 4.00 p.m.

Body weight, amount of urine output will be measured hourly.

Blood and urine samples will be sent to measure the concentration at 0900, 1200, 1500 and 1600.

In normal people, hourly urine output will drop and will become more concentrated as you had no fluid intake. Body weight and blood concentration will remain the same.

If you have Diabetes insipidus due to lack of ADH, you will continue to produce large amounts of urine despite having taken in no fluid. The urine remains diluted, body weight falls and blood become more concentrated as you become dehydrated.

At 1600 hr DDAVP (manufactured medicine similar to natural ADH) will be injected and you will be allowed to take fluid. Urine and blood collections will continue up until 2000hr.

The aim is to assess the body’s response to a lack of fluids and then the response after an injection of DDAVP.

AFTER THE TEST

On completion your venflon will be removed and you will be offered refreshments prior to going home.

Who will get the results?

Your doctor will be informed of the results.

GENERAL MATTERS

Please note that Clinical Investigation Unit has no smoking policy.

If you have any queries or worries, please do not hesitate to contact the nursing staff for further information on 01382 632494.

We hope to make your stay as pleasant as possible.

 
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NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a person’s health provider.