How will u estimate GFR?
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"glomerular filtration rate" AND estimation
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NIDDK eGFR equations CKD-EPI creatinine cystatin C estimate GFR
Estimate GFR (eGFR) mainly from serum creatinine, adjusted for age and sex.
Adults
Use the 2021 CKD-EPI creatinine equation:
[
eGFR=142 \times min(SCr/\kappa,1)^{\alpha} \times max(SCr/\kappa,1)^{-1.200} \times 0.9938^{Age} \times 1.012;[if\ female]
]
- SCr = serum creatinine in mg/dL
- For females: (\kappa=0.7,\ \alpha=-0.241)
- For males: (\kappa=0.9,\ \alpha=-0.302)
- Result is in mL/min/1.73 m²
- This is a race-free equation. In routine practice the laboratory reports it automatically.
For better accuracy, especially if a value will affect drug dosing or transplant assessment, use the combined creatinine plus cystatin-C CKD-EPI equation. NIDDK guidance notes that this is more accurate and less biased than creatinine alone.
Children
Use bedside Schwartz formula:
[
eGFR = \frac{0.413 \times height;(cm)}{serum\ creatinine;(mg/dL)}
]
For drug dosing
Many drug labels still use Cockcroft-Gault creatinine clearance:
[
CrCl = \frac{(140-age)\times weight;(kg)}{72\times SCr}
]
Multiply by 0.85 in females.
Important limitations
- Do not rely on creatinine-based eGFR in rapidly changing renal function, such as acute kidney injury.
- It can be inaccurate with extremes of muscle mass, malnutrition, amputation, pregnancy, bodybuilders, or a high meat intake.
- If an exact GFR is required, measure clearance of an exogenous filtration marker such as iohexol or nuclear-medicine tracers. A 24-hour urine creatinine clearance can be used but tends to overestimate true GFR because creatinine is also secreted by renal tubules.
Calculate eGFR from a patient’s creatinine, age, and sex
Reading File
Please give the patient’s age, sex at birth, and serum creatinine with units (mg/dL or µmol/L).
Asking for Preferences
Which values should I use for the calculation?
Estimate GFR (eGFR) mainly from serum creatinine, adjusted for age and sex.
Adults
Use the 2021 CKD-EPI creatinine equation:
[
eGFR=142 \times min(SCr/\kappa,1)^{\alpha} \times max(SCr/\kappa,1)^{-1.200} \times 0.9938^{Age} \times 1.012;[if\ female]
]
- SCr = serum creatinine in mg/dL
- For females: (\kappa=0.7,\ \alpha=-0.241)
- For males: (\kappa=0.9,\ \alpha=-0.302)
- Result is in mL/min/1.73 m²
- This is a race-free equation. In routine practice the laboratory reports it automatically.
For better accuracy, especially if a value will affect drug dosing or transplant assessment, use the combined creatinine plus cystatin-C CKD-EPI equation. NIDDK guidance notes that this is more accurate and less biased than creatinine alone.
Children
Use bedside Schwartz formula:
[
eGFR = \frac{0.413 \times height;(cm)}{serum\ creatinine;(mg/dL)}
]
For drug dosing
Many drug labels still use Cockcroft-Gault creatinine clearance:
[
CrCl = \frac{(140-age)\times weight;(kg)}{72\times SCr}
]
Multiply by 0.85 in females.
Important limitations
-
Do not rely on creatinine-based eGFR in rapidly changing renal function, such as acute kidney injury.
-
It can be inaccurate with extremes of muscle mass, malnutrition, amputation, pregnancy, bodybuilders, or a high meat intake.
-
If an exact GFR is required, measure clearance of an exogenous filtration marker such as iohexol or nuclear-medicine tracers. A 24-hour urine creatinine clearance can be used but tends to overestimate true GFR because creatinine is also secreted by renal tubules.Please give the patient’s age, sex at birth, and serum creatinine with units (mg/dL or µmol/L).Please provide:
-
Age in years
-
Sex: male or female
-
Serum creatinine and unit: mg/dL or µmol/L
Example: “62-year-old female, creatinine 1.4 mg/dL.”
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