Sapiens · Renal
KFT / RFT Test: Normal Ranges and How to Read Your Kidney Report
A kidney function test — KFT, or RFT for renal function test; the two names mean the same panel — hands you a column of numbers and no meaning. That gap is where the worry usually starts. A creatinine that looks "high" might just be your gym habit; an eGFR that looks "normal" might be quietly drifting. It's easy to panic at one out-of-range value, or wave it away — and neither is right. Here's how to actually read the panel: what each marker means, when an out-of-range number is genuinely nothing, and when it's the one to follow up.
Quick facts
- A KFT/RFT checks creatinine, urea, eGFR, uric acid and electrolytes — how well your kidneys filter.
- Typical normal creatinine is about 0.7–1.3 mg/dL (men) and 0.6–1.1 mg/dL (women); an eGFR of 90 or above suggests normal filtration.
- One out-of-range value is not a diagnosis — hydration, diet, muscle mass and age all move the numbers.
- Diabetes and high blood pressure are the two leading causes of kidney damage, and both are common in India.
- The trend over time tells you far more than a single reading.
What does a KFT/RFT test measure? Copy link
The test estimates kidney filtration and the balance of substances your kidneys regulate. Creatinine is a waste product from muscle that healthy kidneys clear, so a rising level can signal reduced filtration. Blood urea reflects protein breakdown and kidney clearance. eGFR converts your creatinine, age and sex into an estimate of how well your kidneys are working, as a percentage of normal. Uric acid and electrolytes round out the picture, since the kidneys manage these too. Together they're a snapshot of renal health and a baseline to track. (KFT and RFT — Kidney and Renal Function Test — are two names for the same panel.)
| Marker | Typical normal range | Also moved by |
|---|---|---|
| Serum creatinine | 0.7–1.3 mg/dL (men) 0.6–1.1 mg/dL (women) | Muscle mass, creatine supplements, high-protein or meat-heavy meals, hard exercise, dehydration |
| Blood urea | 15–45 mg/dL (BUN 7–20 mg/dL) | Dietary protein, dehydration, gastrointestinal bleeding |
| eGFR | ≥ 90 mL/min/1.73m² | Age (falls naturally), muscle mass, and the equation your lab uses |
| Uric acid | 3.4–7.0 mg/dL (men) 2.4–6.0 mg/dL (women) | Diet, alcohol, genetics, some diuretics |
| Sodium (Na⁺) | 135–145 mmol/L | Hydration, diuretics, some medications |
| Potassium (K⁺) | 3.5–5.1 mmol/L | Kidney function, medications, sample handling |
What is a normal KFT/RFT range? Copy link
The ranges above are typical adult values, but reference intervals shift with age, sex, muscle mass and the lab's method. One practical habit: read each result against the range printed on your report, and against your own previous results, rather than a number you found online. eGFR in particular falls naturally with age, so a value of 60–89 can be normal for an older adult while it would call for a closer look in a young one.2
Do you need to fast for a KFT, and how much does it cost? Copy link
Fasting is generally not required for a kidney function test. It becomes necessary only when the KFT is bundled with tests that do need it — most often fasting glucose or a lipid profile, in which case you would fast 8–12 hours with water allowed. Some doctors also suggest avoiding a heavy meat meal the evening before, since dietary protein can nudge both creatinine and urea upwards.
Cost in India (as of July 2026) typically runs from roughly ₹400 to ₹1,000 for a standard panel, varying with city, laboratory and how many analytes are included; combined LFT + KFT packages are usually cheaper than booking each separately. Turnaround is normally the same day or within 24 hours. Home sample collection is now widely available.
Two other preparation points matter more than fasting: stay normally hydrated (a dehydrated sample raises both creatinine and urea), and tell the lab if you take creatine, protein supplements or any regular medication, since several of these alter the numbers.
What does a high creatinine or low eGFR mean? Copy link
A high creatinine or an eGFR below the normal range can mean the kidneys are filtering less effectively — but it can also reflect temporary or harmless factors: dehydration, a high-protein or creatine-supplemented diet, intense exercise, or simply higher muscle mass. This isn't a loophole — it's well established that creatine supplementation nudges serum creatinine up with no significant change in estimated GFR, because more creatine simply means more creatinine produced.3 Creatinine is a genuinely useful marker, but it has these non-kidney influences built in.2
A genuinely and persistently reduced eGFR is what prompts a doctor to look further.
What does high blood urea or high uric acid mean? Copy link
Raised blood urea can point to reduced kidney clearance, but also to dehydration, a high-protein diet or recent bleeding in the gut — so it's read alongside creatinine and eGFR rather than alone. High uric acid links to gout and diet and is influenced by how the kidneys handle it; whether it needs action depends on symptoms and the rest of your results. In both cases the number is a prompt for interpretation, not a verdict.
What are the other lines on your KFT report? Copy link
A typical Indian KFT prints more than five analytes — often ten to twelve. If you're holding a report with lines the sections above didn't cover, here's what they are.
| Line on your report | Typical range | What it tells your doctor |
|---|---|---|
| Chloride (Cl⁻) | 98–107 mmol/L | Moves with sodium; helps interpret acid–base and hydration status |
| Bicarbonate (HCO₃⁻) | 22–29 mmol/L | Acid–base balance; falls in advanced kidney disease |
| Calcium | 8.5–10.5 mg/dL | Kidneys help regulate it; disturbed in longstanding kidney disease |
| Phosphorus | 2.5–4.5 mg/dL | Rises as filtration falls; watched in later-stage disease |
| Albumin | 3.5–5.2 g/dL | Blood protein made by the liver; low levels have many causes |
| Total protein | 6.4–8.3 g/dL | Albumin plus globulins |
| A/G ratio | 1.0–2.1 | Albumin-to-globulin ratio, calculated from the two above |
| BUN : creatinine ratio | ~6–25 | A calculated ratio; above roughly 20 points towards dehydration rather than kidney tissue damage4 |
Most of these are supporting context rather than headline numbers. Creatinine, eGFR and urine albumin remain the ones that decide whether anything needs action.
Why does your report say urea when other sites say BUN? Copy link
This trips up a lot of people comparing an Indian report against information written elsewhere. Most Indian labs report blood urea — the whole urea molecule. Many international sources report BUN (blood urea nitrogen), which measures only the nitrogen part of that same molecule. They describe the same thing on two different scales.
The conversion is fixed chemistry: urea's molecular weight is 60 and the nitrogen in it is 28, so blood urea ≈ BUN × 2.14.4 A BUN of 14 mg/dL is roughly a blood urea of 30 mg/dL. So a urea of 38 on an Indian report is not "double" a Western normal — it's the same value counted differently. Check which one your report actually names before comparing it to anything.
One related number your doctor may use is the BUN-to-creatinine ratio, typically around 6–25 in adults. A disproportionately high ratio (above about 20) points towards reduced blood flow to the kidneys — most often plain dehydration — rather than damage to the kidney tissue itself.4 It's one more reason a single raised urea is interpreted alongside the other markers, not alone.
Can your kidneys be damaged if creatinine is normal? Copy link
Yes. Filtration is only one of the two things guidelines actually measure. The other is whether the kidney's filters are leaking, which is picked up by a urine test for albumin (a protein), reported as the urine albumin-to-creatinine ratio, or uACR.
Kidney disease is staged on both axes at once: eGFR categories (G1–G5) and albuminuria categories — A1 below 30 mg/g, A2 from 30–300, A3 above 300.5 A raised uACR is an early marker of kidney damage that can appear while eGFR is still completely normal, particularly in people with type 2 diabetes.5 That's why a reassuring creatinine on its own doesn't fully close the question if you have diabetes or high blood pressure — the urine test is what catches the early leak.
A standard blood-only KFT doesn't include it, so if you're in a higher-risk group ask whether a urine albumin test belongs alongside your panel. It's a small addition that changes what the results can actually tell you.
What if you have high muscle mass or take creatine? Copy link
Creatinine comes from muscle, so people with a lot of muscle generate more of it and can show a "high" creatinine with entirely healthy kidneys. The test that settles it is cystatin C, a different filtration marker that is not meaningfully affected by muscle mass.
The National Kidney Foundation names this use case directly: a cystatin C test can give a more accurate result than creatinine if you are older or carry a lot of muscle, such as a bodybuilder.6 KDIGO's 2024 guideline goes further and recommends that where cystatin C is available, the GFR category should be estimated from creatinine and cystatin C together (reported as eGFRcr-cys), because the combination is more accurate than creatinine alone.7
On creatine supplements specifically, the magnitude is now well quantified. A 2026 meta-analysis of 19 randomised trials found creatine raised serum creatinine by about 0.13 mg/dL on average, with no significant difference in urea or estimated GFR. Because eGFR is calculated from creatinine, it moves mechanically when creatinine does. The rise reflects greater creatinine production from a larger creatine pool rather than reduced filtration; neither trial measured GFR directly.10 That is a real but small shift — enough to nudge a borderline result over a cut-off, not enough to explain a substantially abnormal one. If you lift seriously or supplement, mention it before the test, and ask whether cystatin C is the appropriate follow-up rather than assuming either the best or the worst.
Why does the same creatinine give different eGFRs at different labs? Copy link
eGFR is not measured. It is calculated from your creatinine, age and sex using an equation — and Indian laboratories do not all use the same one. Some still report the older MDRD equation; others use CKD-EPI, which since its 2021 revision no longer includes a race coefficient.9
The difference is not trivial. In the US NHANES dataset, the same population had a median eGFR of 85.0 mL/min/1.73m² by MDRD versus 94.5 by CKD-EPI, and an estimated CKD prevalence of 13.1% versus 11.5%.8 (That is US data, so it shows the size of the equation effect rather than Indian prevalence.) In other words, identical creatinine values can land on either side of a clinical threshold depending only on which formula the lab applied.
This has a practical consequence for anyone tracking kidney function over time: comparing an eGFR from one lab against an eGFR from another can show a "change" that is really just a change of equation. Two habits fix it — check which equation your report names (it is usually printed next to the eGFR), and where possible use the same laboratory for repeat testing so the trend is genuinely comparable.
Why do diabetes and high blood pressure matter for your kidneys? Copy link
Long-term high blood sugar and high blood pressure are the two leading causes of kidney damage, and both are common in India — the ICMR-INDIAB study estimated 101 million adults with diabetes and around 35% of adults with hypertension.1 That's why people with these conditions are advised to monitor kidney function over time: managing blood sugar and blood pressure well is the main way to protect the kidneys, and a tracked KFT catches early change while it's most manageable. The framing here is monitoring and management, not cure. Reduced kidney function also raises cardiovascular risk, which is why a KFT is usually read alongside your lipid profile results.
What are the symptoms of kidney problems? Copy link
Early kidney disease usually causes nothing at all, which is why it is typically found on a blood test rather than by how you feel.2 When symptoms do appear, the common ones are:
- Swelling (oedema) around the ankles, feet or eyes, often worse in the morning
- Foamy or frothy urine that persists — a possible sign of protein leaking into the urine
- Changes in urination: passing much more or much less, or getting up repeatedly at night
- Fatigue and poor concentration, sometimes with anaemia
- Muscle cramps, itching, nausea or loss of appetite
- Blood pressure that has become harder to control
None of these is specific to the kidneys on its own. Any of them, and especially several together, is a reason to have kidney function checked rather than to self-diagnose.
When should you get a KFT, and how often? Copy link
A KFT sits at the centre of kidney health testing and is commonly included in a full-body health check, and is advised more regularly for people with diabetes, high blood pressure, a family history of kidney disease, or those on long-term medications that affect the kidneys. How often depends on your individual risk and is best set with a doctor. As with most lab markers, a KFT tracked over time is far more informative than a one-off reading — which is also why it pairs naturally with your HbA1c and blood-sugar results rather than being read in isolation.
What should you do if your KFT is abnormal? Copy link
An out-of-range KFT is a reason to have the result interpreted properly — alongside your other markers — long-standing kidney disease, for example, often shows up as anemia on a CBC (complete blood count) — your history, and ideally a repeat test — not a reason to panic or to self-treat. The useful next step is understanding why it's off and what, if anything, needs to change. A lab report gives you numbers without the meaning, and that's the gap to close. Discuss any abnormal result with a qualified doctor.
What should you know about getting a KFT in India? Copy link
KFT full form and RFT full form. KFT stands for Kidney Function Test; RFT stands for Renal Function Test. They are the same panel, and Indian labs use the names interchangeably — you may also see "renal profile" or "kidney profile" on a requisition.
Choosing a lab. Look for NABL accreditation, which indicates the laboratory meets national testing-quality standards. Because eGFR equations and reference intervals vary between labs, staying with one accredited laboratory makes your results comparable over time.
LFT and KFT together. Liver and kidney panels are frequently ordered as a pair, and the combination is usually priced below the sum of the two. If a doctor has asked for both, book them as one draw.
Home collection. Home sample collection is now widely offered across major Indian labs, which suits the three-times-a-year monitoring that people with diabetes or high blood pressure are advised to keep up. The scale of the need is substantial: population screening in India has put chronic kidney disease prevalence at around 17%,11 and the Indian CKD Registry identifies diabetic kidney disease as the single leading cause nationally, at about 31% of cases.11
When should you see a doctor? Copy link
See a doctor if a KFT is persistently abnormal, if you have swelling or reduced urine output, or if you have uncontrolled diabetes or blood pressure — and any time you're unsure how to interpret a result. A single mildly off value, repeated when well-hydrated, is often nothing — but a doctor should make that call.
Frequently asked questions Copy link
What is a KFT test?
A KFT (Kidney/Renal Function Test) is a group of blood tests — creatinine, urea, eGFR, uric acid and electrolytes — that shows how well your kidneys are filtering.
What is the difference between KFT and RFT?
None — Kidney Function Test and Renal Function Test are two names for the same panel.
Is a slightly high creatinine serious?
Not necessarily — it can reflect dehydration, diet or muscle mass. It's the trend and the full picture, interpreted by a doctor, that matter.
What eGFR is considered normal?
An eGFR of 90 or above suggests normal filtration. 60–89 is mildly reduced and can be normal with age; below 60 for more than three months is how chronic kidney disease is defined and warrants follow-up.
Is blood urea the same as BUN?
They measure the same waste product on different scales. Blood urea is the whole molecule; BUN counts only its nitrogen. Blood urea is roughly BUN × 2.14, so a BUN of 14 mg/dL is about a blood urea of 30 mg/dL. Check which one your report names before comparing values.
Can kidney damage exist with a normal creatinine?
Yes. Creatinine and eGFR measure filtration, but the kidneys can also leak protein while filtration still looks normal. A urine albumin-to-creatinine ratio (uACR) above 30 mg/g signals damage even with a normal eGFR, which is why urine albumin is recommended alongside blood tests for people with diabetes or high blood pressure.
Do I need to fast for a KFT test?
Generally no — a kidney function test does not require fasting. Fasting is only needed if the KFT is bundled with a test that requires it, such as fasting glucose or a lipid profile (8–12 hours, water allowed). Stay normally hydrated, and mention any creatine or protein supplements.
How much does a KFT test cost in India?
Typically around ₹400–₹1,000 for a standard panel, depending on city, laboratory and the number of analytes included. Combined LFT + KFT packages usually cost less than booking both separately, and results are normally available the same day or within 24 hours.
Does creatine or gym training raise creatinine?
Yes, modestly. A 2026 meta-analysis of 19 randomised trials found creatine supplementation raised serum creatinine by about 0.13 mg/dL with no significant change in eGFR. Higher muscle mass does the same. If this applies to you, a cystatin C test — which is not affected by muscle mass — gives a more accurate picture.
Why is my eGFR different at a different lab?
Because eGFR is calculated, not measured, and Indian labs use different equations. The same creatinine gives a different eGFR under MDRD versus CKD-EPI — in NHANES data, median eGFR was 85.0 by MDRD and 94.5 by CKD-EPI. Check which equation your report names, and use the same lab for repeat tests so the trend is comparable.
What are the early symptoms of kidney problems?
Early kidney disease usually has no symptoms. When they appear, common ones are swelling around the ankles or eyes, persistently foamy urine, passing much more or less urine, fatigue, muscle cramps and blood pressure that has become harder to control. None is specific to the kidneys, so testing rather than self-diagnosis is the right step.
References Copy link
- Anjana RM, Unnikrishnan R, Deepa M, et al. Metabolic non-communicable disease health report of India: the ICMR-INDIAB national cross-sectional study (ICMR-INDIAB-17). The Lancet Diabetes & Endocrinology. 2023;11(7):474–489 — 101 million adults with diabetes, ~35% with hypertension. PMID 37301218
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney International. 2024;105(4S):S117–S314 — eGFR categories (G1 ≥90, G2 60–89, CKD <60 for >3 months); do not assume chronicity from a single abnormal value; non-GFR determinants of creatinine (muscle mass, diet, medications); early CKD is often silent. kdigo.org
- Effect of creatine supplementation on kidney function: a systematic review and meta-analysis. BMC Nephrology. 2025 — creatine causes a small, transient rise in serum creatinine with no significant change in GFR (a production effect, not renal impairment). PMID 41199218
- Blood Urea Nitrogen (BUN): Reference Range, Interpretation. Medscape — urea's molecular weight is 60 and its nitrogen fraction 28, so blood urea ≈ BUN × 2.14; the BUN-to-creatinine ratio typically runs about 6–25 in adults, and a ratio above roughly 20 indicates reduced renal perfusion (commonly dehydration) rather than intrinsic kidney damage. emedicine.medscape.com
- KDIGO Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease — Chapter 1: Definition and classification of CKD. Kidney International Supplements — CKD is classified by GFR categories G1–G5 together with persistent albuminuria categories A1 (uACR <30 mg/g), A2 (30–300) and A3 (>300); raised albuminuria is an early marker of kidney damage that can precede any fall in eGFR. kdigo.org
- Cystatin C. National Kidney Foundation — a cystatin C blood test can give a more accurate eGFR than creatinine when a person is older or has a lot of muscle (for example, a bodybuilder), because creatinine varies with muscle mass. kidney.org/kidney-topics/cystatin-c
- KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease — Executive Summary. Kidney International — where cystatin C is available, the GFR category should be estimated from combined creatinine and cystatin C (eGFRcr-cys); do not assume chronicity from a single abnormal eGFR or ACR. kdigo.org
- Levey AS, Stevens LA, Schmid CH, et al. A new equation to estimate glomerular filtration rate. Annals of Internal Medicine. 2009;150(9):604–612 — among 16,032 NHANES 1999–2006 participants, median eGFR was 94.5 (CKD-EPI) vs 85.0 mL/min/1.73m² (MDRD), and CKD prevalence 11.5% (95% CI 10.6–12.4) vs 13.1%. US data; it demonstrates the size of the equation effect, not Indian prevalence. PMC2763564
- Inker LA, Eneanya ND, Coresh J, et al. New Creatinine- and Cystatin C-Based Equations to Estimate GFR without Race. New England Journal of Medicine. 2021;385(19):1737–1749 — the 2021 CKD-EPI creatinine equation removes the race coefficient. PMID 34554658
- Tsiaras A, et al. The effect of creatine supplementation on kidney function: a systematic review and meta-analysis of randomized controlled trials. Journal of Renal Nutrition. Published online April 2026 — across 19 RCTs, creatine raised serum creatinine by a mean 0.13 mg/dL (95% CI 0.07–0.18) with no significant difference in urea or eGFR. jrnjournal.org
- Prevalence of impaired kidney function and its association with diabetes and hypertension in India: the ICMR–INDIAB study (ICMR-INDIAB-22). Indian Journal of Medical Research. 2025 — reviews Indian CKD prevalence estimates including the SEEK study figure of 16–17%; per the Indian CKD Registry, diabetic kidney disease is the leading cause of CKD nationally (31.1%). ijmr.org.in
Medical disclaimer. This article is for general information and is not a substitute for professional medical advice, diagnosis or treatment. Reference ranges, thresholds and prices vary by laboratory and location. Always discuss your own results with a qualified doctor before making any decision about testing or treatment.
Written by Dr. Tarun Reddy, MBBS · Updated 5 August 2026 · Report an error on this page