Creatinine Clearance is a more accurate way to detect changes in kidney status than measurement of serum urea and creatinine, which are easier to do but cannot pick up early damage to the kidneys. If kidney damage is detected early, it may be possible to prevent further damage, with treatment of high blood pressure, diabetes, or other diseases that can damage the kidney. eGFR or calculated creatinine clearance is based on serum creatinine, an easily performed and commonly used laboratory test. The calculation of eGFR which has been adopted in the UK uses a formula which uses the concentration of creatinine in blood, the age and sex of the patient and their ethnic origin.

Since April 2006 eGFR 'estimated GFR' or calculated Creatinine Clearance has been routinely offered by the majority of UK laboratories. It has been introduced to improve the detection of early kidney damage so that measures can be taken to the stop or to at least to slow progression to more severe kidney damage. eGFR is suitable for most patients who are 18 or more years old, not pregnant or malnourished and do not have acute kidney damage. GPs and UK laboratories are now using eGFR to look for the presence of kidney damage in various 'at risk groups' including people with diabetes, blood vessel disease, heart problems, high blood pressure, obstructions to urines flow and in patients taking some commonly prescribed drugs including diuretics (water tablets) and a variety of drugs used to treat high blood pressure.

eGFR or Calculated Creatinine Clearance is a simple test to detect early changes in kidney function. A normal result means that kidney disease is less likely while a low value suggests that some kidney damage has occurred. Creatinine Clearance results are usually evaluated in the same way. Sometimes, in very early kidney damage (especially when the kidneys are damaged by diabetes), measured or estimated clearance may actually be high, indicating that the kidneys are working harder than normal.

Creatinine Clearance can increase during pregnancy.