How to prepare
No fasting is required. Drink water as normal and stay well hydrated.
Let your practitioner know about any high-protein diet changes, recent dehydration, or medications you take regularly, as all of these can affect urea levels. Avoid eating an unusually large amount of protein in the 24 hours before the test if you want a representative result. A healthcare professional will take a blood sample from a vein in your arm.
After the test
Share your results with your GP or relevant specialist. If urea is elevated alongside creatinine and a low eGFR, your practitioner may investigate kidney function further. If urea is elevated but creatinine is normal, dehydration or dietary factors are more likely and may be assessed first.
Your test results will be available in your private dashboard. If there are any urgent issues, we'll let you know so you can follow up with your health professional.
Understanding results
Results are reported in millimoles per litre (mmol/L). The typical adult reference range is approximately 2.5 to 7.5 mmol/L, though this can vary between laboratories.
Elevated urea can indicate reduced kidney filtration, dehydration, a high-protein diet, increased protein catabolism (such as during illness, injury, or prolonged fasting), or gastrointestinal bleeding. The urea-to-creatinine ratio is useful here: a disproportionately elevated urea compared to creatinine often points to dehydration or gastrointestinal bleeding rather than intrinsic kidney disease.
Low urea can occur with low protein intake, liver disease (where urea production is reduced), or overhydration.
Your practitioner will interpret urea alongside creatinine, eGFR, and your clinical context.
