Calc Function

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    CKD-EPI Equations for Glomerular Filtration Rate (GFR)

    Estimates GFR based on serum creatinine, serum cystatin C, or both.
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    When to Use
    Pearls/Pitfalls
    Why Use
    • Patients with chronic kidney disease (not acute), to measure renal function.
    • CKD-EPI Cystatin C is preferred in cirrhotics and other patients with low muscle mass.
    • CKD-EPI Creatinine can be used in settings where cystatin C is not available.  
    • Creatinine-based estimates of kidney function by glomerular filtration rate (GFR) are less accurate in certain populations including diabetics with high GFR, pregnant women, those with unusual body mass (obese, severely malnourished, amputees, paraplegics, etc).
    • Cystatin C-based estimates vary based on factors still being studied including age, race and gender.
    • Creatinine estimates alone are more accurate than cystatin C-based estimates.
    • Used together, creatinine and cystatin C estimates are more accurate than using either alone.

    The CKD-EPI equation performs superiorly to the MDRD Equation in patients with normal or mildly reduced estimated GFR (eGFR), and just as well in patients with less than normal eGFR.

    About the Creator
    Dr. Andrew S. Levey
    Content Contributors
    • Omar Aziz, MD

    Result:

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    Next Steps
    Evidence
    Creator Insights

    Advice

    Patients with deranged GFR need dose adjustments for renally-cleared medications.

    Management

    Patients should be classified in stages of CKD for grading severity, mortality, and management and referred early to a nephrologist.

    CKD Stage

    GFR (ml/min/1.73 m2)

    I

    ≥90

    II

    60–89

    III

    30–59

    IV

    15–29

    V

    <15

    Formula

    CKD-EPI Creatinine = A × (Scr/B)C × 0.993age × (1.159 if black), where A, B, and C are the following:

    Female

    Male

    Scr ≤0.7

    A = 144

    B = 0.7

    C = -0.329

    Scr ≤0.9

    A = 141

    B = 0.9

    C = -0.411

    Scr >0.7

    A = 144

    B = 0.7

    C = -1.209

    Scr >0.9

    A = 141

    B = 0.9

    C = -1.209

     

    CKD-EPI Cystatin C = 133 × (Scys/0.8)A × 0.996age × B, where A and B are the following:

     

    Female

    Male

    Scys ≤0.8

    A = -0.499

    B = 0.932

    A = -0.499

    B = 1

    Scys >0.8

    A = -0.499

    B = 0.932

    A = -0.499

    B = 1

     

    CKD-EPI Creatinine–Cystatin C = A × Scr/BC × (Scys/0.8)D × 0.995age × (1.08 if black), where A, B, C, and D are the following:

    Female:

     

    Scr ≤0.7

    Scr >0.7

    Scys ≤0.8

    A = 130

    B = 0.7

    C = -0.248

    D = -0.375

    A = 130

    B = 0.7

    C = -0.601

    D = -0.375

    Scys >0.8

    A = 130

    B = 0.7

    C = -0.248

    D = -0.711

    A = 130

    B = 0.7

    C = -0.601

    D = -0.711

    Male:

     

    Scr ≤0.9

    Scr >0.9

    Scys ≤0.8

    A = 135

    B = 0.9

    C = -0.207

    D = -0.375

    A = 135

    B = 0.9

    C = -0.601

    D = -0.375

    Scys >0.8

    A = 135

    B = 0.9

    C = -0.207

    D = -0.711

    A = 135

    B = 0.9

    C = -0.601

    D = -0.711

    Scr, serum creatinine. Scys, serum cystatin C.

    Facts & Figures

    CKD Stage

    GFR (ml/min/1.73 m2)

    I

    ≥90

    II

    60–89

    III

    30–59

    IV

    15–29

    V

    <15

    Evidence Appraisal

    The original CKD-EPI (creatinine) was developed by Levey et al in 2009, who measured GFR of 8,254 participants using clearance of iothalamate. Linear regression was used to estimate the logarithm of measured GFR from standardized creatinine levels, sex, race, and age.

    The equation was validated by Inker et al (2012) and found to be more accurate than the MDRD Equation (percentage of estimated GFR within 30% of measured GFR was 84.1% vs. 80.6%). The sensitivity and specificity of estimated GFR <60 ml/min/1.73 m2 were 91% and 87%, respectively, using the CKD-EPI equation and 95% and 82%, respectively, using the MDRD Equation.

    Dr. Andrew S. Levey

    About the Creator

    Andrew S. Levey, MD, is the chief of the nephrology division at Tufts Medical Center and the Dr. Gerald J. and Dorothy R. Friedman Professor at Tufts University School of Medicine. His clinical interests include chronic kidney disease (CKD), diabetic kidney disease, and systemic lupus erythematosus. Dr. Levey’s research focuses on laboratory measures to estimate kidney function, new therapies, and the development of clinical practice guidelines for CKD.

    To view Dr. Andrew S. Levey's publications, visit PubMed

    Content Contributors
    • Omar Aziz, MD