DEVELOPMENT OF A NONISOTOPIC CAPILLARY ELECTROPHORESIS-BASED METHOD FOR MEASURING GLOMERULAR-FILTRATION RATE

The conditions for quantitative measurement of nonisotopic iothalamate meglumine (Conray) in urine and plasma by capillary zone electrophore sis (CE) have been developed. The impetus for developing this methodol ogy was to replace the traditional [I-125]iothalamate glomerular filtr ation rate (GFR) marker assay, a routine tool in the measurement of ki dney function. This new approach for measuring kidney function is attr active since it avoids the cost of administration of radioisotopic com pounds to patients, as well as the cost associated with purchase and d isposal of isotopic compounds and contaminated samples. The concentrat ion of iothalamate in urine and plasma determined by CE can be used di rectly to calculate GFR. The GFR in patients injected with [I-125]ioth alamate and nonisotopic iothalamate simultaneously showed an excellent correlation (0.998) with between-day coefficient of variation of 2.30 % and a recovery of 102% and 98%, respectively, when added to urine an d plasma. Interference from drugs and other urinary compounds is elimi nated with this method. Collectively, this study has shown that CE is a cost-effective alternative to the current methodology for measuring GFR.