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What Does GFR Stand for in Kidney Function?

Kidney disease makes it difficult for the kidneys to maintain fluid and electrolyte balances and filter waste products from the body. GFR is a useful measurement that describes how well a patient's kidneys are functioning.

  1. Definition

    • GFR stands for "glomerular filtration rate." This measurement determines how well the kidneys are able to remove waste products from the blood.

    Calculation

    • Formulas used to calculate a patient's glomerular filtration rate are complex. Dr. Stephen Z. Fadem, vice president of the board of directors of the American Association of Kidney Patients, explains that it is possible to estimate a patient's GFR using age, gender, race and the amount of creatinine in the blood, among other factors. Creatinine is a waste product produced when proteins are broken down in the body.

    Disease Staging

    • GFR is used to determine the stage of chronic kidney disease, or CKD. Kidney damage and a GFR above 90 indicate a patient has stage one CKD. Stage two is indicated by a GFR from 60 to 89, stage three is indicated by a GFR from 30 to 59 and stage four is indicated by a GFR from 15 to 29. Kidney failure, or stage five chronic kidney disease, is indicated by a GFR below 15.

    Weaknesses

    • When GFR is based on blood creatinine levels, the estimate may not be completely accurate. For example, patients who eat a high-protein diet have more creatinine in the blood, which can skew GFR results. Laboratory testing errors can also yield an inaccurate GFR estimate.

    Further Testing

    • Creatinine blood testing must be done to estimate GFR. If a patient's GFR is below normal, additional tests are performed to measure levels of sodium, potassium, phosphorus and blood urea nitrogen (BUN) in the blood.

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