eGFR

Keywords: Estimated glomerular filtration rate, Estimated GFR

Specimen:

Serum or plasma for creatinine measurements; see Creatinine.

The patient should not eat a cooked meat meal for 4 - 6 h prior to testing.

Method:

Estimated GFR (eGFR) is a derived value.

  1. eGFR (mL/min/1.73m2) is calculated by the pathology laboratory using the patient's age, sex and serum creatinine result.

    The result is expressed relative to a 'standard' body surface area of 1.73m2.

  2. Generally calculated using the CKD-EPI formula.

Reference Interval:

> 90 mL/min/1.73m2 - normal GFR

60 - 89 mL/min/1.73m- mild reduction in GFR (note: this is a very common finding and only likely to indicate pathological changes if serum creatinine is above reference interval or there is other evidence of renal damage).

30 - 59 mL/min/1.73m- moderate reduction in GFR

15 - 29 mL/min/1.73m- severe reduction in GFR

<15 mL/min/1.73m- end stage kidney damage

NOTE: There is an expected fall with age of approximately 0.5 mL/min/1.73m2 per annum.

Application:

Assessment of glomerular filtration rate, which is the main indicator of kidney function.

Interpretation:

Moderate, severe or end-stage reduction in GFR persisting for more than 3 months indicates Chronic Kidney Disease. Rapid reductions may indicate acute renal failure.

Important Notes:

eGFR is accurate to approx +/- 30%

Reduced accuracy in extremes of body composition, eg extreme muscularity, obesity, emaciation, paraplegia etc.

While likely to be appropriate, eGFR is not validated in all racial groups and should be interpreted with caution.

Not suitable for use in children, pregnancy, dialysis.

If result is uncertain, formal GFR measurement or Creatinine clearance may be indicated.

Reference:

KDIGO 2012 Clinical Practice Guideline for the Evaluation and Management of Chronic Kidney Disease. Kidney International supplements 2013;3:1-150