How to Test GFR

Glomerular Filtration Rate (GFR) is a calculated value that estimates the amount of kidney function a person has. The calculation uses creatinine levels for the baseline and then adjusts the value by factoring in age, race and gender. GFR is considered the best way to measure kidney function and the state of kidney disease. While GFR can be determined by a lab during blood testing, it can also be determined if serum creatinine levels are known.

Things You'll Need

• Creatinine blood test
• Calculator

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Instructions

• 1

  Obtain a blood creatinine test and determine the serum creatinine level.

• 2

  Multiply the serum creatinine level (in units of mg/dL) by the exponent of -1.154 to obtain the serum creatinine adjusted value.

• 3

  Multiply the person's age by the exponent of -0.203 to obtain the age adjusted value.

• 4

  Multiply 175 by the the serum creatinine, then multiply by the age-adjusted value from step three.

• 5

  If the person is female, multiply the value by 0.742.

• 6

  If the person is African American, multiply the value by 1.212.

• 7

  The result of this equation is the GFR value. The units for the result are mL/min/1.73 m^2.

• 8

  Compare the test results to the values for each stage of kidney damage according to the National Kidney Foundation (Reference 1). If the GFR number is 90 or above, then kidney function is normal. If the GFR number is between 60 and 89, additional evaluations may be needed to understand if the value is normal when age, medications and medical history are considered. If the GFR number is below 60, then kidney function is abnormal and medical attention should be sought.