OBJECTIVE: The objective of this article is to review and evaluate the various 
parameters used in determining renal status.
CONCLUSION: The physiologic determination of renal status is the measured 
glomerular filtration rate (mGFR). Serum creatinine, blood urea nitrogen, 
cystatin C, and estimated GFR (eGFR), based on serum creatinine have failed to 
replace mGFR. All physicians should be aware of limitations of substituted mGFR.