Synonyms: Estimated glomerular filtration rate, eGFR
Related tests: Uric acid, Urea, Creatinine, Creatinine clearance, Albuminuria, complete urinalysis
Clinical significance
Estimating the glomerular filtration rate (GFR) from blood creatinine is based on the principle that for every halving of GFR, serum creatinine doubles; in our laboratory we use the simplified MDRD formula of Levey et al., normalised for a standard body surface area of 1.73 m², which is valid for the adult population but not for pregnant women or severely debilitated people.
GFR falls in all situations where blood flow to the kidneys is reduced: haemorrhagic shock, dehydration, congestive heart failure, glomerulonephritis, nephrotic syndromes, pyelonephritis, amyloidosis, acute tubular dysfunction, interstitial nephritis, etc.
Clinical indications
Estimation of the glomerular filtration rate.
Sample type
The patient must have a blood sample taken.
Preparation
Avoid intense exercise in the 8-12 hours before the blood test.
Notes
It should be remembered that in chronic kidney failure creatinine is also eliminated through the renal tubules, and the resulting increase in urine creatinine leads creatinine clearance to overestimate glomerular filtration. This is why it is preferable to estimate glomerular filtration directly from serum creatinine.