The estimated glomerular filtration rate (eGFR) is a critical measure for assessing kidney function, aiding in the diagnosis and management of kidney disease.

**Formulas for Estimating eGFR**

Three primary formulas are used to estimate eGFR:

1. Modification of Diet in Renal Disease (MDRD) Study equation

2. Cockcroft-Gault formula

3. Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation.

**MDRD Study Equation**

eGFR=175×(Serum Creatinine)^(−1.154)×(Age)^(−0.203)×(0.742 if Female)×(1.212 if African American)

**Cockcroft-Gault Formula**

CrCl=[(140−Age)×Weight×(0.85 if Female)] / [72×Serum Creatinine]

Where weight is in kilograms. While this formula estimates creatinine clearance (CrCl), it is closely related to eGFR and often used interchangeably in clinical practice.

**CKD-EPI Equation**

eGFR=141×min[(Serum Creatinine)/k,1]^*a* ×max[(Serum Creatinine)/k,1)^(−1.209)×0.993^Age×(1.018 if Female)×(1.159 if African American)

Where 𝑘 is 0.7 for females and 0.9 for males, 𝑎 is -0.329 for females and -0.411 for males.

**Common Usage**

Among these formulas, the **CKD Epidemiology Collaboration (CKD-EPI)** equation is the most commonly used by laboratories. It offers more accurate eGFR estimates across different levels of kidney function, particularly at higher GFR levels, and is recommended by many clinical guidelines.

**Example 1**

**Patient Details**:

Serum Creatinine: 1.2 mg/dL

Age: 50 years

Sex: Female

Race: African American

**CKD-EPI Calculation:**

eGFR = 141× min(1.2/0.7,1)^{-0.329} × max(1.2/0.7,1)^{−1.209} × 0.993^{50} × 1.018 × 1.159

So, eGFR ≈ 61

**Example 2**

**Patient Details**:

Serum Creatinine: 0.9 mg/dL

Age: 65 years

Sex: Male

Race: Caucasian

**MDRD Calculation:**

eGFR = 175 × 0.9^(−1.154) × 65^(−0.203)

So, eGFR ≈ 85

**Unit for eGFR**

The unit for eGFR is mL/min/1.73m². It indicates the volume of blood (in milliliters) that the kidneys can filter per minute, normalized to a standard body surface area (BSA) of 1.73 square meters. This standardization allows for comparison across individuals of different sizes and body compositions, ensuring that the eGFR values are not biased by body size.

**Quiz**

Please note that our articles are not intended to guide personal health decisions.