What Is Renal Function (Kidney Function)? What means GFR?

Your health care team may talk about the work your kidneys do in terms of kidney function. If you have two healthy kidneys, you have 100 percent of your kidney function. This is more than you really need. Some people are born with only one kidney and are still able to live a normal and healthy life. Many people donate a kidney for transplantation to a family member or friend and continue to have a relatively normal kidney function. Small declines in renal function do not necessarily cause a problem.

However, many people with reduced kidney function have a kidney disease that will worsen over time. Serious health problems occur when kidney function declines to less than 25 percent. If it drops below 10 to 15 percent, a person cannot live long without some form of renal replacement therapy - either dialysis or transplantation.

One common measure of kidney function is the glomerular filtration rate (GFR). GFR describes how many millilitres of blood the kidneys are able to filter within one minute. The normal value is 90 ml/min or higher. Often you will see GFR values with the unit ml/min/1.73 m2, because technically, GFR is expressed in relation to body surface area, which averages 1.73 m2. If your GFR is too low, your kidneys may not be able to remove enough wastes and extra water from your blood. Your GFR can be estimated from a routine measurement of creatinine in your blood. Creatinine is a waste product formed by the normal breakdown of muscle cells; the amount of creatinine correlates with kidney function.

The creatinine concentration in the blood serum begins to rise quite late in the disease process – when kidney function (GFR) has decreased to about 50 %.

Content last updated
  1. KDOQI Clinical Practice Guidelines for Chronic Kidney Disease: Evaluation, Classification, and Stratification. Am J Kidney Dis 2002; 39 (Suppl 1): 1-222. http://www.kidney.org/professionals/KDOQI/guidelines_ckd/p5_lab_g4.htm (last visited 30.03.2010)
  2. Thews G, Mutschler E, Vaupel P: Anatomie, Physiologie, Pathophysiologie des Menschen. Wissenschaftliche Verlagsgesellschaft 2007
  3. National Kidney Foundation http://www.kidney.org/kidneydisease/ckd/knowGFR.cfm#chart (last visited 30.03.2010)