Calcand

GFR Calculator (Kidney Function)

years
mg/dL

Normal range: 0.7-1.3 mg/dL (men), 0.6-1.1 mg/dL (women)

CKD Stages

Stage 1 - NormalGFR 90+
Stage 2 - Mild decreaseGFR 60-89
Stage 3a - Mild-moderateGFR 45-59
Stage 3b - Moderate-severeGFR 30-44
Stage 4 - Severe decreaseGFR 15-29
Stage 5 - Kidney failureGFR <15

Formula Comparison

CKD-EPI 2021

Current standard. Race-free equation. Most accurate for GFR >60.

MDRD

Older formula. Better for GFR <60. Includes race coefficient.

Cockcroft-Gault

Estimates creatinine clearance. Requires weight. Used for drug dosing.

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Understanding GFR and Kidney Function

Glomerular Filtration Rate (GFR) is the best test to measure kidney function. It estimates how much blood passes through the glomeruli (tiny filters in the kidneys) each minute. A normal GFR is typically above 90 mL/min/1.73m2.

What is Creatinine?

Creatinine is a waste product from normal muscle metabolism. Healthy kidneys filter creatinine from the blood. When kidney function declines, creatinine levels rise. The GFR is estimated based on blood creatinine levels along with age, sex, and other factors.

Risk Factors for Kidney Disease

  • Diabetes: Leading cause of kidney disease
  • High blood pressure: Second leading cause
  • Heart disease: Linked to kidney problems
  • Family history: Genetic factors play a role
  • Age: Kidney function naturally declines with age
  • Obesity: Increases strain on kidneys

Protecting Your Kidneys

Do

  • Stay hydrated
  • Control blood pressure
  • Manage blood sugar
  • Exercise regularly
  • Eat a balanced diet

Avoid

  • Excessive salt intake
  • NSAIDs overuse (ibuprofen)
  • Smoking
  • Excessive protein intake
  • Dehydration

Medical Disclaimer

This calculator provides an estimate only. Actual GFR can only be measured through clinical tests. If you have concerns about kidney function, please consult a healthcare provider. A single creatinine measurement may not reflect true kidney function - trends over time are more informative.

Frequently Asked Questions

What is GFR and what does it measure?

GFR (Glomerular Filtration Rate) measures how well your kidneys filter waste from your blood. It estimates how much blood passes through the tiny filters (glomeruli) in your kidneys each minute, measured in mL/min/1.73m2. A normal GFR is 90 or above. Lower values indicate reduced kidney function.

What do the CKD stages mean?

CKD (Chronic Kidney Disease) stages indicate kidney function levels. Stage 1 (GFR 90+): Normal function. Stage 2 (GFR 60-89): Mildly decreased. Stage 3a (GFR 45-59): Mild to moderate decrease. Stage 3b (GFR 30-44): Moderate to severe decrease. Stage 4 (GFR 15-29): Severely decreased. Stage 5 (GFR under 15): Kidney failure.

What is creatinine and why is it used to calculate GFR?

Creatinine is a waste product from normal muscle metabolism that healthy kidneys filter from the blood. When kidney function declines, creatinine builds up in the blood. By measuring blood creatinine levels along with age and sex, eGFR formulas can estimate kidney filtration rate without more invasive testing.

Which GFR formula should I use?

The CKD-EPI 2021 equation is the current standard, as it's race-free and most accurate for GFR above 60. The MDRD equation may be more accurate for GFR below 60. Cockcroft-Gault estimates creatinine clearance (not GFR) and is still used for drug dosing. Your healthcare provider will use the appropriate formula.