Kidney Function Calculator
Comprehensive renal function assessment with eGFR calculations and CKD staging
Patient Information
kg
Required for Cockcroft-Gault
cm
Required for pediatric calculations
Kidney Function Assessment
This calculator provides comprehensive kidney function assessment using validated equations. The CKD-EPI 2021 equation is currently recommended as the primary method for eGFR calculation.
| Stage | Description | GFR Range | Risk Level | Key Actions |
|---|---|---|---|---|
1 | Normal or high kidney function | ≥90 mL/min/1.73 m² | Low | • Diagnose and treat underlying cause• Cardiovascular risk reduction |
2 | Mildly decreased kidney function | 60-89 mL/min/1.73 m² | Low-Moderate | • Estimate progression• Cardiovascular risk reduction |
3 | Moderately decreased kidney function | 30-59 mL/min/1.73 m² | Moderate-High | • Evaluate and treat complications• Slow progression |
4 | Severely decreased kidney function | 15-29 mL/min/1.73 m² | High | • Prepare for kidney replacement therapy• Specialist referral |
5 | Kidney failure | <15 mL/min/1.73 m² | Very High | • Kidney replacement therapy• Palliative care considerations |
CKD-EPI 2021
Most current equation without race adjustment, recommended by KDIGO 2024
eGFR = 142 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(-1.200) × 0.9938^age × 1.012 [if female]CKD-EPI 2009
Previous standard equation with race adjustment (historical reference)
eGFR = 141 × min(Scr/κ, 1)^α × max(Scr/κ, 1)^(-1.209) × 0.993^age × 1.018 [if female] × 1.159 [if Black]MDRD Study Equation
Older equation, less accurate but historically important
eGFR = 175 × Scr^(-1.154) × Age^(-0.203) × 0.742 [if female] × 1.212 [if Black]Cockcroft-Gault
Estimates creatinine clearance, not indexed to BSA
CrCl = [(140-age) × weight] / (72 × Scr) × 0.85 [if female]Schwartz Pediatric
Specifically developed for children and adolescents
eGFR = k × Height / Scr (k varies by age and gender)Understanding Kidney Function Assessment
Comprehensive guide to eGFR calculations, CKD staging, and clinical interpretation for healthcare professionals.
🧮 eGFR Calculation Methods
Multiple validated equations are available for estimating glomerular filtration rate:
CKD-EPI 2021
Current gold standard without race adjustment. Most accurate across populations.
CKD-EPI 2009
Previous standard with race coefficient. Useful for historical comparison.
MDRD Study
Older equation, less accurate but historically important reference.
Cockcroft-Gault
Estimates creatinine clearance. Useful for drug dosing decisions.
📊 CKD Staging System
Chronic kidney disease classification based on eGFR levels:
Stage 1: ≥90 - Normal/High function
Stage 2: 60-89 - Mildly decreased
Stage 3: 30-59 - Moderately decreased
Stage 4: 15-29 - Severely decreased
Stage 5: <15 - Kidney failure
🏥 Clinical Applications
Key uses of kidney function assessment in clinical practice:
CKD Screening: Early detection and classification of chronic kidney disease
Drug Dosing: Adjusting medication doses based on kidney function
Progression Monitoring: Tracking changes in kidney function over time
Referral Decisions: Determining need for nephrology consultation
🔬 CKD-EPI 2021 Equation
The current gold standard for eGFR calculation, removing race-based adjustments:
eGFR = 142 × min(Scr/κ, 1)α × max(Scr/κ, 1)-1.200 × 0.9938age × 1.012 [if female]
κ (kappa): 0.7 (female) or 0.9 (male)
α (alpha): -0.241 (female) or -0.302 (male)
Scr: Serum creatinine (mg/dL)
Units: mL/min/1.73 m²
Key Advantage: Provides more equitable kidney function assessment across all racial and ethnic groups.
📋 Clinical Guidelines
Evidence-based recommendations for kidney function assessment:
KDIGO 2024 Guidelines
Recommend CKD-EPI 2021 as primary eGFR equation without race coefficient.
NKF Recommendations
Support transition to race-neutral eGFR equations for clinical practice.
ASN Guidelines
Endorse implementation of CKD-EPI 2021 in clinical laboratories.
Important: Always interpret eGFR results in clinical context, considering other markers like albuminuria and medical history.
⚠️ Special Considerations
Important factors to consider when interpreting kidney function results:
Elderly Patients
Age-related decline in GFR is normal. Consider functional status and comorbidities.
Pregnancy
GFR increases during pregnancy. Standard equations may not apply.
Extremes of Body Size
Very obese or underweight patients may require adjusted interpretation.
Acute Conditions
eGFR may not accurately reflect kidney function during acute illness.
🔍 Quality Assurance & Best Practices
Laboratory Considerations
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Use standardized creatinine assays (IDMS-traceable)
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Ensure proper specimen collection and handling
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Consider timing of sample collection (steady state)
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Account for interfering substances in creatinine measurement
Clinical Interpretation
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Always consider clinical context and patient history
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Include albuminuria assessment for complete CKD evaluation
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Monitor trends rather than single point measurements
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Consider confirmatory testing for significant changes
Evidence-Based Medicine
This calculator implements current evidence-based guidelines from major nephrology organizations including KDIGO, NKF, and ASN. The CKD-EPI 2021 equation represents the latest advancement in kidney function estimation, providing more equitable assessment across diverse populations while maintaining clinical accuracy and reliability.
Last updated based on: KDIGO 2024 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease
⚠️ Important Medical Disclaimer
This kidney function calculator is designed for use by qualified healthcare professionals only. Results should be interpreted in the context of the patient's clinical presentation, medical history, and other relevant diagnostic information. This tool does not replace clinical judgment or professional medical consultation.
eGFR calculations are estimates and may not accurately reflect actual kidney function in all patients. Consider additional testing such as measured GFR, albuminuria assessment, and imaging studies when clinically indicated. Always follow current clinical guidelines and institutional protocols.
For emergency situations or acute changes in kidney function, seek immediate medical attention and do not rely solely on calculated estimates.