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When you are diagnosed with high blood pressure, your doctor or nurse will probably wish to carry out a simple test of your urine to check how well your kidneys and other organs are working.
A simple urine test can reveal a lot about how high blood pressure is affecting your body, but sometimes your doctor may want more detailed information. If they would like to know more about how your body is working, they may ask for a sample of your urine that is collected over 24 hours.
How is a simple urine test carried out?
Your doctor will ask for a small sample of urine – around 10-15mls (roughly a tablespoon). They will test the sample using specially treated dipsticks which change colour to show how much protein, blood, or sugar your urine contains.
What can a simple urine test show?
A simple urine test can reveal a lot about how your body is working:
- if there is a small amount of protein in the urine, then you may have a problem with your kidneys
- if there is a small amount of blood in the urine, then you may have a problem with your kidneys or bladder
- if sugar is found in your urine, then you may have diabetes.
How is a 24-hour urine test carried out?
If you are asked to supply a 24-hour urine test, you will be given a bottle to use, to collect all the urine your kidneys make over a 24-hour period.
How to collect a 24-hour sample:
- start collecting your urine in the morning between 6.00am and 10.00am. Write down the exact time you start
- when you start, empty your bladder and discard all the urine. Then put all the urine you produce over the next 24 hours into the sample bottle
- exactly 24 hours after starting, empty your bladder whether you need to or not into the bottle
- bring the sample in to your hospital or surgery on the same day it is completed.
On rare occasions you may be asked to collect your urine in a bottle containing a small amount of acid. If this is the case, you will need to be careful not to spill it or burn yourself. Once the acid is diluted with the first urine sample, it is no longer dangerous.
What can a 24-hour urine test show?
The larger volume of urine and longer collection time of a 24-hour test can reveal:
- how much salt you are eating
- how well your kidneys are working
- if you have a rare form of high blood pressure called phaeochromocytoma
- if you have a condition called Cushing’s syndrome.
If you develop high blood pressure while you are pregnant, a 24-hour urine test can show if this is due to pre-eclampsia.
Do I need to do anything before a urine test?
There is no need to do anything differently because you’re being tested. Both the dipstick urine test and the 24-hour urine test are designed to look at how your body is working on a normal day, so it is important to eat and drink, and behave, as normal.