Blood Urea

Kidney function

Urea is a waste product formed in the liver when the body breaks down protein. It travels in the blood to the kidneys, which remove it in the urine. This test measures urea in your blood to help check how well the kidneys are working, and it also reflects how well hydrated you are and how much protein you have been eating.

• To check kidney function, usually together with creatinine
• During vomiting, diarrhoea or dehydration
• To monitor people with kidney disease, heart failure or diabetes
• If there may be bleeding in the stomach or upper gut, which can raise urea

Eat and drink normally, and try not to become dehydrated before the test, as this raises urea. An unusually large high-protein meal shortly beforehand can also raise it a little. Keep taking your regular medicines unless your doctor has told you otherwise.

Sample

Blood sample

How it works

A trained collector takes a small sample of blood from a vein in your arm at home. It takes only a few minutes, and the same sample can be used if your doctor has also asked for creatinine.

Report

Within 24 hours of collection.

The report shows your urea next to the laboratory's reference range. A high urea can be caused by kidney problems, dehydration, a high-protein diet, bleeding in the gut or some medicines, while a low urea can be seen with liver disease, a low-protein diet or pregnancy. Because many things affect it, your doctor will interpret urea alongside creatinine.

One test: Blood Urea, from one blood sample.