Understanding glomerular filtration rate

Glomerular filtration rate (GFR) is the best single measure of kidney function. A subnormal GFR is an important early indicator of possible chronic kidney disease. However, it also does not identify the cause. It is also not a ‘catch all’, for example, in early diabetes mellitus, GFR will typically be normal or even increased, due to ‘hyperfiltration’.

Optimal detection and risk stratification of early kidney disease also requires measurement of urine albumin, rather than just eGFR.

Estimating GFR

Creatinine clearance (qv) has been used to estimate GFR, but requires an accurate 24-hour urine collection, making it an unsuitable screening test.

Serum creatinine (qv) alone has often been used as a simple screen but is strongly influenced by muscle mass, diet and other factors, which are hard to quantify. A ‘normal’ result may be falsely reassuring in patients with ...

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