GFR is not an orderable procedure.
In adults, glomerular filtration rate can be easily estimated using the modified MDRD GFR equation. This formula uses the patient's age and sex with the measured blood creatinine value to estimate GFR, allowing patients with earlier stages of kidney disease to be identified.
Blood Creatinine laboratory reports for all adult outpatients will include a report of GFR estimated by the MDRD equation.
The MDRD GFR calculation is available on the web site: http://www.nephron.com/cgi-bin/MDRD_GFR.cgi | 
