Glomerular Filtration Rate (GFR) Calculation

A glomerular filtration rate (GFR) is a blood test that checks how well the kidneys are filtering. It is defined as the sum of the filtration rates of all your functioning nephrons (filtering units making up the kidneys).

GFR Calculation Formula

1. CKD-EPI Creatinine Equation (2009)

Calculation Variables:

• For females, the following values are used: Sex Factor = 1.018; alpha = -0.329; kappa = 0.7
• For males, the following values are used: Sex Factor = 1; alpha = -0.411; kappa = 0.9
• For race, American Indian or Alaska Native is 1; Asian is 1; Black or African American is 1.159; Native Hawaiian or Other Pacific Islander is 1; White is 1.

2. CKD-EPI Equation without Race (2021)

Calculation Variables:

• For females, the following values are used: Sex Factor = 1.012; alpha = -0.241; kappa = 0.7
• For males, the following values are used: Sex Factor = 1; alpha = -0.302; kappa = 0.9

3. MDRD Study Equation (SI units)

Calculation Variables:

• For Female, sex factor is 0.742
• For Male,  sex factor is 1
• For Black or African American, race factor is 1.21
• For Non-Black, race factor is 1

Estimated GFR (eGFR) values are classified as follows:

• eGFR of 90 or higher is in the normal range
• eGFR of 60–89 may mean early kidney disease
• eGFR of 15–59 may mean kidney disease
• eGFR below 15 may mean kidney failure

GFR values can also be classified as follows:

• Normal: 100-140 mls/min,
• Mild Kidney Failure < 90 mls/min,
• Moderate Kidney Failure < 60mls/min,
• Severe Kidney Failure < 30 mls/min, and
• End-stage Kidney Failure < 15mls/min, which is incompatible with life, without dialysis or transplantation.