GFR (Glomerular Filtration Rate) Definition

Renal function describes how well the kidneys are working. Glomeruli are the unit of filtration for our kidneys and are composed of several parts. As blood passes through these glomeruli from other parts of the body, waste materials are filtered out for excretion. One of those waste materials is creatinine. A measure of the serum creatinine level – that is the amount in the blood – can be a useful tool for helping determine kidney function.

The Glomerular Filtration Rate (GFR) is a test used to describe the level of current kidney function. There are many different formulas used to calculate the GFR using many different factors. This GFR Calculator uses just a few simple factors to determine a person’s current kidney function. You will need to obtain a blood test with a creatinine level before using this calculator.

The pieces of information you enter in the Glomerular Filtration Rate calculator include:

  1. Age (in years)
  2. Weight (in pounds)
  3. Serum Creatinine (in milligrams(mg)/deciliter(dL)
  4. Gender

The calculator will give you results – expressed in milliliters per minute – based on the Cockcroft-Gault GFR scale. This scale is used to determine one of the six stages or severity of chronic kidney disease (CKD). The stages are described as follows:

  • Normal kidney function – GFR greater than or equal to 90 mL/min with no other evidence of kidney damage
  • CKD1 – GFR greater than or equal to 90 mL/min with evidence of kidney damage
  • CKD2 – GFR equal to 60-89 mL/min
  • CKD3 – GFR equal to 30-59 mL/min
  • CKD4 – GFR equal to 15-29 mL/min
  • CKD5 – GFR less than 15 mL/min

GFR (Glomerular Filtration Rate) Formula:

((140 - age) x Mass in kg x [0.85 if female]) / (72 x Serum Creatinine in mg/dL)