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Are you over 60? MedlinePlus names that as a reason to have your kidneys checked. Early kidney disease usually causes no symptoms, and a urea test can bring a problem like that to light early.[1]
On this page you can read what urea is, what the guidelines say about a level that is too low or too high, what affects your level and which values are best to set beside it.
Also known as: urea, urea nitrogen, blood urea nitrogen (BUN). At the lab: HST.
Urea is a waste product. It forms when your body breaks down proteins. Your blood carries it to your kidneys, and they remove it when you pass urine.[1]
A small amount of urea in your blood is normal. The test is often part of a wider set of blood tests for your metabolism. You may also come across it as a blood urea nitrogen test or BUN.[1]
If your kidneys are not working as well as they should, urea can build up in your blood. According to MedlinePlus, this can lead to serious health problems, including anaemia and problems with the heart and blood pressure.[1]
Early kidney disease often causes no symptoms. That is why a doctor may have your urea measured during a routine check-up, or to follow how a level changes while your kidneys are being cared for.[1]
MedlinePlus also names reasons to have your kidneys checked: kidney problems in the family, a heart condition, problems with blood sugar or blood pressure, being over 60 and smoking.[1]
Your doctor may also measure urea if you have symptoms such as passing urine often or very little, itching, tiredness, swelling in your arms, legs or feet, muscle cramps and poor sleep.[1]
Labplusarts, the lab BioProfile works with, uses a reference range of 2.77 to 8.1 mmol/l for urea (HST). The lab calls a level between those limits normal.[2]
| Value | What the lab says | Who it is for |
|---|---|---|
| 2.77 to 8.1 mmol/l[2] | Normal according to the lab | The lab does not name a separate group |
Source: Labplusarts, the lab BioProfile works with. Reference range for urea (HST) at this lab.[2]
A level below normal can point to too little protein in your diet, malnutrition or a liver condition. What your result means is something to discuss with your doctor.[1]
A level above normal can point to kidneys that are not working as well. Other possible reasons are too little fluid in your body, burns, certain medicines, a high-protein diet or a recent acute heart problem. An abnormal result does not always point to something that needs care.[1]
BioProfile is working on its own zones for each value, from risk to optimal. A doctor reviews those zones before they appear in your result.
If you eat a lot of protein, your urea may come out higher. If you get too little protein, it may come out lower.[1]
If you have too little fluid in your body, your urea can rise.[1]
Certain medicines can raise your urea. If you take any medicines, tell your doctor when you discuss your result.[1]
Urea can differ between men and women. It usually rises with age.[1]
Urea is included in BioProfile 77, 98, 121 and 150.[3]
The BioProfile editorial team wrote this page on 7 October 2026 from the sources below, which we read on 7 October 2026. Every number on this page appears in one of those sources, with that source's number next to it. An expert has yet to check this page; after that check, the expert's name and the date of the check will appear at the top. This page explains and does not give a diagnosis. Discuss an abnormal result with your GP.
