Understanding Your Kidney Function Tests (KFT / RFT) Results
Kidney Function Tests (also called Renal Function Tests or RFT) assess how well your kidneys filter waste products from the blood. Serum creatinine is a muscle metabolism waste product cleared exclusively by the kidneys — it rises as kidney filtration declines. eGFR (estimated glomerular filtration rate) is calculated from creatinine, age, sex, and sometimes ethnicity to give a standardised filtration capacity in mL/min/1.73m². BUN (blood urea nitrogen) is another waste marker. Electrolytes — sodium, potassium, bicarbonate, and chloride — reflect the kidneys' role in fluid and acid-base balance. Together these markers stage chronic kidney disease (CKD) and detect acute kidney injury.
Normal Reference Ranges
>>>| Parameter | Normal Range | Unit | Note |
|---|---|---|---|
| Creatinine — Men | 0.7–1.3 | mg/dL | — |
| Creatinine — Women | 0.6–1.1 | mg/dL | Lower due to less muscle mass |
| BUN (Blood Urea Nitrogen) | 7–20 | mg/dL | — |
| BUN:Creatinine Ratio | 10–20 | ratio | Elevated in dehydration |
| eGFR — Normal | > 90 | mL/min/1.73m² | Normal kidney function |
| eGFR — Mildly decreased | 60–89 | mL/min/1.73m² | Monitor annually |
| eGFR — Moderate CKD | 30–59 | mL/min/1.73m² | Nephrology referral |
| eGFR — Severe CKD | < 30 | mL/min/1.73m² | Specialist care required |
Reference ranges may vary slightly between laboratories. Always compare your result to the range printed on your specific lab report.
What High Kidney Function Tests (KFT / RFT) Results Mean
Elevated creatinine and a reduced eGFR indicate impaired kidney filtration. The rate of decline matters as much as the absolute value — a rapid rise in creatinine over days to weeks signals acute kidney injury (AKI), which may be due to dehydration, infection, nephrotoxic drugs (NSAIDs, contrast dye, aminoglycoside antibiotics), or obstruction. A gradual rise over months to years indicates chronic kidney disease (CKD), most commonly caused by diabetic nephropathy or hypertensive nephrosclerosis. High potassium (hyperkalaemia, above 5.5 mEq/L) is a dangerous complication of advanced kidney disease and can cause fatal cardiac arrhythmias. Elevated BUN with normal creatinine (high BUN:creatinine ratio above 20) often indicates dehydration rather than kidney disease.
What Low Kidney Function Tests (KFT / RFT) Results Mean
Very low creatinine is usually seen in individuals with low muscle mass (elderly, malnourished, paraplegic) — in these cases, creatinine may be misleadingly normal even with significantly reduced kidney function. Cystatin C, a different filtration marker, is more reliable in low-muscle-mass patients. Low BUN (below 7 mg/dL) can indicate severe liver disease (the liver produces urea), low protein intake, or over-hydration.
When to See a Doctor
Seek urgent medical care if creatinine rises acutely (by 0.3 mg/dL or more within 48 hours), if potassium exceeds 6.0 mEq/L (cardiac emergency), if urine output drops significantly, or if eGFR falls below 30 mL/min/1.73m² — this stage typically requires specialist nephrology care and planning for potential dialysis in the future. Any person with diabetes or hypertension and creatinine above the reference range should see a doctor, even if they feel well.
UAE Health Context
CKD is a growing public health crisis in the UAE, directly linked to the world's highest diabetes and hypertension rates. The UAE Renal Registry reports approximately 1,200 new patients commencing dialysis annually, with diabetic nephropathy the leading cause. Dehydration — from the extreme heat, particularly among outdoor manual workers (predominantly South Asian) — is a significant and under-recognised cause of AKI in the UAE. NSAIDs such as ibuprofen and diclofenac are widely self-purchased over the counter at UAE pharmacies and are a common preventable cause of AKI. Uric acid is often added to KFT panels in UAE labs given the high rates of gout in the South Asian male expat population.
What to Do Next
For mildly reduced eGFR (60–89): increase water intake, avoid nephrotoxic drugs (NSAIDs, high-dose supplements), control blood pressure below 130/80 mmHg, and optimise diabetes control if relevant. Retest in 3–6 months. For eGFR 30–59: nephrology referral, urine albumin:creatinine ratio to quantify kidney damage, dietary protein moderation, and strict cardiovascular risk management. For eGFR below 30: specialist care, medication dose adjustments, AV fistula planning for possible dialysis, and discussion of renal replacement therapy options.
Related Tests Often Ordered Together
>>>Frequently Asked Questions
What is a normal Kidney Function Tests (KFT / RFT) level?
Normal Kidney Function Tests (KFT / RFT) ranges vary by parameter. Creatinine — Men: 0.7–1.3 mg/dL; Creatinine — Women: 0.6–1.1 mg/dL; BUN (Blood Urea Nitrogen): 7–20 mg/dL; BUN:Creatinine Ratio: 10–20 ratio; eGFR — Normal: > 90 mL/min/1.73m²; eGFR — Mildly decreased: 60–89 mL/min/1.73m²; eGFR — Moderate CKD: 30–59 mL/min/1.73m²; eGFR — Severe CKD: < 30 mL/min/1.73m². Always compare your results against the reference range on your specific lab report, as ranges can vary slightly between laboratories.
What causes high Kidney Function Tests (KFT / RFT)?
Elevated creatinine and a reduced eGFR indicate impaired kidney filtration. The rate of decline matters as much as the absolute value — a rapid rise in creatinine over days to weeks signals acute kidney injury (AKI), which may be due to dehydration, infection, nephrotoxic drugs (NSAIDs, contrast dye, aminoglycoside antibiotics), or obstruction. A gradual rise over months to years indicates chronic kidney disease (CKD), most commonly caused by diabetic nephropathy or hypertensive nephrosclerosis. High potassium (hyperkalaemia, above 5.5 mEq/L) is a dangerous complication of advanced kidney disease and can cause fatal cardiac arrhythmias. Elevated BUN with normal creatinine (high BUN:creatinine ratio above 20) often indicates dehydration rather than kidney disease.
Do I need to fast before a Kidney Function Tests (KFT / RFT) test?
No, fasting is not required for this test. It can be done at any time of day without dietary restrictions.
How often should I get a Kidney Function Tests (KFT / RFT) test?
Annually for anyone with diabetes or hypertension. Every 3–6 months for known CKD.
Medical Disclaimer: The information on this page is provided for general educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Reference ranges are general guidelines — your doctor will interpret your results in the context of your full clinical picture, symptoms, and medical history. If you have concerns about your test results, always consult a licensed healthcare professional. Do not delay seeking medical advice or disregard professional medical guidance because of information on this page.