[header] How to increase gfr [title] Take the test. [step] Your doctor can test your gfr by administering a creatinine blood test. Creatinine is a waste product present in your blood. 
If the amount of creatinine contained within a sample is too high, your kidneys' filtering ability (gfr) is likely too low. [substeps] Alternatively, your doctor might administer a creatinine clearance test, which measures the amount of creatinine in both your blood and urine.