What it measures
- Urea
What is a urea blood test?
Urea is made in the liver when your body breaks down protein. It travels in the blood to the kidneys, which filter it out into your urine. Measuring the urea in your blood gives a quick picture of how well your kidneys are clearing waste, and whether you might be dehydrated.
Understanding your result
Urea is best read alongside creatinine and eGFR, which give a more precise measure of kidney filtration. A slightly high urea is often caused by not drinking enough, a high-protein diet or some medicines. If you’d like a fuller picture, our Kidney Function Blood Test measures urea together with creatinine, eGFR and key electrolytes.
Who it’s for
- A quick check of kidney function
- Tiredness, swelling or changes in how often you pass urine
- Monitoring hydration or a high-protein diet
How to prepare
- Drink plenty of water beforehand; it makes the sample quicker and easier to take.
- You don’t need to fast.
- Avoid a very large, protein-rich meal in the few hours before your test.
Urea Blood Test: your questions
What can cause a high urea level?
Dehydration is the most common cause. A high-protein diet, some medicines, bleeding in the gut and reduced kidney function can also raise urea.
Is urea the same as uric acid?
No. Urea is a waste product of protein that the kidneys clear. Uric acid comes from the breakdown of purines and is linked to gout. This test measures urea.
Information on this page is general and doesn’t replace advice from your GP, midwife or consultant. If you feel unwell or are worried about symptoms, contact your GP, call NHS 111 or, in an emergency, 999.