Test library
BUN to Creatinine Ratio Test
The BUN/Creatinine Ratio Test compares blood urea nitrogen to creatinine to help assess kidney function and hydration status. The relationship between the two values can suggest whether kidney, liver, or other factors are at play.
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Order BUN/Creatinine Ratio Test- Typical turnaround
- 1-3 business days
- Starting price
- From $39
- Results
- Confidential, online
Quick answer
The BUN/Creatinine Ratio Test measures two related blood values, blood urea nitrogen and creatinine, and compares them in a single calculation. It is used to help assess kidney function, hydration, and some gastrointestinal or liver concerns. The ratio is not a stand-alone diagnosis; a healthcare provider interprets it with the full clinical picture and other laboratory findings.
What this test measures
Blood urea nitrogen, or BUN, is a waste product formed when the liver breaks down protein, and it is cleared by the kidneys. Creatinine is a waste product from normal muscle activity that is also filtered by the kidneys. Comparing the two gives a ratio that adds context beyond either value alone, because they can change at different rates when kidney function, hydration, or protein intake shifts.
The test uses a standard blood sample drawn from a vein. Results are reported as a calculated ratio, typically alongside the individual BUN and creatinine concentrations. Because the ratio depends on both numbers, laboratories and clinicians review the underlying values rather than the ratio in isolation. Conditions such as dehydration, a high-protein diet, gastrointestinal bleeding, or liver disease can influence the balance.
Clinicians may order this ratio when a routine metabolic panel shows an unexpected BUN or creatinine level, or when they are evaluating kidney function, hydration, or a suspected gastrointestinal bleed. It is not a diagnosis on its own, and a qualified healthcare provider should interpret it in the context of symptoms, medications, and other tests.
- Blood urea nitrogen (BUN)
- Creatinine
- BUN/Creatinine ratio
- Estimated glomerular filtration rate (eGFR)
- Sodium
- Potassium
- Chloride
- Carbon dioxide (bicarbonate)
- Glucose
- Calcium
Why people order this test
- Assess kidney function when BUN or creatinine is abnormal
- Evaluate hydration status and dehydration
- Investigate a suspected gastrointestinal bleed
- Support the workup of liver or kidney conditions
- Monitor a known kidney problem over time
- Help interpret a comprehensive metabolic panel
How to prepare
No special preparation is usually required, although some laboratories ask for fasting if the test is bundled with a lipid or glucose panel. A blood sample is drawn from a vein, typically at the arm. Follow the specific instructions supplied with the order.
Understanding your results
Results are typically available within one to three business days. The report shows the BUN and creatinine values and the calculated ratio, which a healthcare provider interprets together with other findings. An abnormal ratio does not diagnose a condition by itself.
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Frequently Asked Questions
What is the BUN/Creatinine ratio?
It is a calculation that compares blood urea nitrogen to creatinine in the blood. The relationship between the two can offer clues about kidney function, hydration, and other conditions.
Do I need to fast for this test?
Fasting is not usually required, but some laboratories request it when the test is combined with a glucose or lipid panel. Follow the instructions provided with the order.
What can cause a high ratio?
Dehydration, a high-protein diet, and gastrointestinal bleeding are among the factors that can raise the ratio. A healthcare provider evaluates the result with the full clinical picture.
What can cause a low ratio?
A low ratio may be seen with liver disease, a low-protein diet, or certain kidney conditions. Interpretation depends on the individual values and other test results.
Is this test the same as a kidney function panel?
No. The ratio is one part of kidney assessment and is often reported within a broader metabolic panel that includes creatinine and an estimated glomerular filtration rate.
Ready to get tested?
Order online and visit a collection site near you, or choose a mail-in kit. No referral and no insurance required.
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