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Discover the complete guide to Kidney Function Test (KFT / RFT). Learn its purpose, how it’s done, test parameters, symptoms of kidney disease, causes, and preventive measures. Stay informed and protect your kidney health.
Kidney Function Test (KFT / RFT) – A Complete A to Z Guide
Introduction
Kidneys are vital organs responsible for filtering waste, regulating electrolytes, balancing fluids, and maintaining overall health. When kidney function declines, it can lead to serious health issues such as chronic kidney disease (CKD), hypertension, or kidney failure.
A Kidney Function Test (KFT), also called Renal Function Test (RFT), is a set of blood and urine tests that assess how effectively your kidneys are working. Early detection through KFT can prevent complications and improve treatment outcomes.
What is a Kidney Function Test (KFT / RFT)?
A Kidney Function Test is not a single test but a panel of investigations designed to measure kidney performance. It evaluates the ability of kidneys to filter blood, remove toxins, regulate electrolytes, and maintain fluid balance.
Why is KFT Done?
Doctors may recommend a KFT in the following situations:
Routine health checkup for early detection of kidney problems
Monitoring patients with diabetes or hypertension, as these conditions affect kidney health
Assessing medication effects, especially long-term drugs that may harm kidneys
Pre-surgical evaluation to ensure kidneys can handle anesthesia and surgery
Detecting electrolyte imbalance that can affect heart and muscles
Tests Included in KFT / RFT
1. Blood Tests
Serum Creatinine: Measures waste from muscle metabolism; high levels indicate kidney dysfunction.
Blood Urea Nitrogen (BUN): High levels suggest reduced kidney function or dehydration.
Uric Acid: Excess may indicate kidney stones or gout.
Serum Electrolytes: Sodium, potassium, chloride, bicarbonate – imbalance may signal kidney disorders.
Estimated Glomerular Filtration Rate (eGFR): Indicates how efficiently kidneys filter blood; low eGFR means impaired function.
2. Urine Tests
Urine Analysis: Detects protein, blood, or abnormal substances.
24-Hour Urine Collection (if required): Measures total protein and creatinine clearance.
Causes for Kidney Function Test
Diabetes mellitus: High blood sugar damages kidney vessels.
Hypertension: Increases pressure on kidney filters.
Urinary tract obstruction: Stones, tumors, enlarged prostate.
Long-term medications: NSAIDs, antibiotics, chemotherapy drugs.
Family history of kidney disease
Diseases Detected by KFT
Chronic Kidney Disease (CKD)
Acute Kidney Injury (AKI)
Kidney stones (Nephrolithiasis)
Glomerulonephritis
Polycystic Kidney Disease (PKD)
Electrolyte imbalance affecting heart/muscles
Symptoms Indicating Need for KFT
Swelling in feet, ankles, or face
Fatigue or weakness
Frequent urination or reduced urine output
Foamy or blood-stained urine
High blood pressure difficult to control
Preparation for KFT
Fasting not always required, but sometimes advised
Avoid high-protein meals before test
Stay hydrated but follow doctor’s instructions
Inform doctor about medications
How KFT is Performed
1. Blood sample – Usually drawn from arm vein
2. Urine sample – Spot or 24-hour collection
3. Laboratory analysis – Tests for creatinine, urea, electrolytes, protein, eGFR
4. Results interpretation – Compared with standard reference ranges
Understanding KFT Results
Parameter Normal Range What Abnormal Results Mean
Serum Creatinine 0.6–1.3 mg/dL High: Kidney dysfunction
BUN 7–20 mg/dL High: Kidney dysfunction or dehydration
eGFR ≥90 mL/min Low: Reduced kidney filtration
Sodium 135–145 mmol/L Imbalance: Kidney/electrolyte disorder
Potassium 3.5–5.0 mmol/L High/Low: Kidney disease, heart risk
Urine Protein <150 mg/day High: Kidney damage
Importance of KFT
Detects kidney disease early, before symptoms appear
Monitors progression of CKD and treatment efficacy
Helps manage medications safely
Guides lifestyle and diet modifications for kidney protection
Lifestyle Measures to Protect Kidneys
Stay hydrated – 6–8 glasses/day
Limit salt intake to control blood pressure
Eat a balanced diet – fruits, vegetables, moderate protein
Exercise regularly – maintains healthy blood pressure and sugar levels
Avoid smoking and excess alcohol
Regular KFT monitoring for at-risk individuals
Frequently Asked Questions (FAQ)
Q1: How often should I do KFT?
Healthy adults: once every 1–2 years
High-risk individuals: 2–4 times a year
Q2: Can diet affect results?
Yes, high-protein meals or dehydration can temporarily alter BUN/urea levels
Q3: Is the test painful?
Minor discomfort from blood draw; urine collection is painless
Q4: Can KFT detect kidney stones?
Indirectly; elevated creatinine or uric acid may indicate stones
Conclusion
The Kidney Function Test (KFT / RFT) is an essential diagnostic tool for maintaining kidney health. It helps detect disease early, monitor treatment, and prevent life-threatening complications. Regular testing, combined with a healthy lifestyle, protects your kidneys and improves overall well-being.
