Kidney Function Test (KFT/RFT)
Blood tests that show how well your kidneys are filtering waste.
Quick Summary
To check kidney health, especially in diabetes, high blood pressure and with some medicines.
Creatinine, urea (BUN), eGFR, sodium, potassium and sometimes uric acid.
Usually no fasting needed.
Overview
Creatinine is a waste product the kidneys remove. From it, labs calculate eGFR, an estimate of kidney filtering.
KFT is part of routine checks for people with diabetes or high blood pressure.
What It Measures
Creatinine
Higher levels mean reduced filtering.
eGFR
Estimated filtering rate.
Urea
Waste product from protein.
Electrolytes
Sodium and potassium.
How It's Performed
- 01
Preparation
Usually no special preparation. Tell the staff about medicines you take.
- 02
Blood sample
A small amount of blood is taken from a vein in your arm with a thin needle.
- 03
Afterwards
Press on the spot for a minute. A small bruise is common; you can go back to normal activities.
Reference Ranges
Note: Normal ranges vary by laboratory. Consult your report for the specific reference used.
| Parameter | Typical Range (Adult) | Units |
|---|---|---|
| Creatinine | 0.6–1.3 | mg/dL |
| eGFR | 90 or above | mL/min/1.73m² |
| Urea nitrogen (BUN) | 7–20 | mg/dL |
| Potassium | 3.5–5.0 | mmol/L |
Interpreting Results & Next Steps
Discuss with Doctor
Normal ranges differ between laboratories, ages and sexes; always use the range printed on your report and ask your doctor what your results mean.
If values are Low:
A low eGFR means the kidneys aren't filtering as well; below 60 for three months suggests chronic kidney disease.
If values are High:
High creatinine or urea can mean kidney problems or dehydration. High potassium needs prompt attention.
Sources and further reading
Last updated 21 October 2026. For more detail, see these trusted health organisations.
- Estimated Glomerular Filtration Rate (eGFR) and GFR Tests(opens in a new tab) · MedlinePlus, US National Library of Medicine
- Creatinine test(opens in a new tab) · MedlinePlus, US National Library of Medicine