GFR DETERMINED BY NONRADIOLABELLED IOTHALAMATE USING CAPILLARY ELECTROPHORESIS

Traditional measurements of glomerular filtration rate (GFR) in clinic al practice include the measurement of serum creatinine or creatinine clearance. Increasing evidence concerning the limitation of these meas urements in clinical practice and clinical trials has resulted in effo rts to develop technologies that improve measurement of GFR, Recent ef forts in that regard have used radioisotopic labeling of markers of GF R, such as I-125-iothalamate, and Cr-51-ethylenediaminetetraacetic aci d. Limitations of these technologies include radiation exposure as wel l as cost considerations for the management of radioisotopes, includin g safety, disposal, mailing, and deteriorating activity that results i n short shelf life. We report a test that used 0.5 mL Conray dye injec ted subcutaneously and subsequent measurement of the nonisotopic (cold ) iothalamate by capillary electrophoresis in blood and urine. GFR usi ng cold iothalamate compared with standard clearance using I-125-iotha lamate was 0.99. The method is cost-effective and allows for avoiding exposure to isotopes, as well as problems such as the disposal and sho rt shelf life of isotopes, This technology could allow for replacement of I-125-iothalamate as a marker for GFR. (C) 1997 by the National Ki dney Foundation, Inc.