Kidney function test (KFT/RFT) blood test

What does the Kidney Function measure?

A KFT measures creatinine, urea, uric acid and the calculated eGFR, sometimes with cystatin C, to estimate kidney filtration.

Why is the Kidney Function ordered?

It is ordered to check kidney health, follow diabetes or high blood pressure, and review hydration and medication effects.

Tests in this panel

Each test links to its own page with named reference-range sources.

Sources: [KDIGO] [CLSI] [American College of Rheumatology (ACR)] [National Kidney Foundation (NKF)]

• CreatinineMuscles produce this waste at a fairly steady daily rate as they burn energy. The kidneys filter it out into urine, so its blood level mirrors how well filtering is happening.
• UreaThe liver forms this compound to package the nitrogen left over from breaking down protein. The kidneys then filter it into urine, so the level reflects both processes.
• Uric AcidThis forms when the body breaks down purines, building blocks found in some foods and in dying cells. The kidneys filter most of it out, and any excess can form sharp crystals.
• eGFRThis is a calculated estimate of the volume of blood the kidneys filter each minute. A formula combines your creatinine level with your age and sex to produce the figure.
• Cystatin CNearly all body cells release this small protein at a constant pace. The kidneys filter it and break it down, so its blood level tracks filtering without depending on muscle mass.
• BUN/Creatinine RatioThe BUN/creatinine ratio compares blood urea nitrogen, a value based on urea, with creatinine. It helps show the pattern behind kidney strain.
• Beta-2 MicroglobulinNearly every cell in your body carries this tiny protein on its surface and sheds it into the blood. It passes into the fine filtering tubes of the kidney, so the level tracks how well those tubes clear it.

Frequently asked questions

What is included in the Kidney Function?

A KFT measures creatinine, urea, uric acid and the calculated eGFR, sometimes with cystatin C, to estimate kidney filtration. It typically reports 7 results: Creatinine, Urea, Uric Acid, eGFR, Cystatin C, BUN/Creatinine Ratio, Beta-2 Microglobulin.

Why is the Kidney Function ordered?

It is ordered to check kidney health, follow diabetes or high blood pressure, and review hydration and medication effects.

How should the Kidney Function be read as a whole?

No single value tells the full story — the results are read together, and each value is compared against the reference range printed on your own report, which can vary by lab, method and equipment.

Do the reference ranges in the Kidney Function vary between labs?

Yes. Ranges depend on the laboratory's equipment and method, so the range printed on your own report is the one that applies to your result. Each test page names the standards body behind its range.