gfr renal glomerular filtration rate insufficiency min ml patients contrast 
gfr glomerular filtration rate min ml estimated creatinine calculated uln 
glomerular filtration rate creatinine min ml gfr mg dl serum 
min ml renal creatinine function gfr glomerular filtration rate adequate 
estimated glomerular filtration rate egfr min ml creatinine renal cockcroft 
radioisotope gfr creatinine glomerular filtration min clearance rate ml serum