[Comparison of single plasma sample methods and prediction of dual plasma sample method in measurement of 99mTc-Diethylene Triamine Pentaacetic Acid plasma clearance].Beijing Da Xue Xue Bao Yi Xue Ban. 2005 Dec 18; 37(6):633-7.BD
To find an applicable condition of the single-plasma-sample method (SPSM) to measure the glomerular filtration(GFR) with (99m)Tcj Diethylene Triamine Pentaacetic Acid ((99m)Tc-DTPA), and predict the value of (99m)Tc-DTPA plasma clearance by dual plasma sample method (DPSM) from that by SPSM.
Three hundred and thirty five patients with chronic kidney disease (CKD) were selected (192 males and 143 females). The average age was 51.91+/-14.76 years. The GFR was determined simultaneously by 2 methods: (1) SPSM (sGFR); (2) DPSM (tGFR), using DPSM as reference standard, sGFR calculated from the different SPSM was compared with tGFR. An equation was developed to predict tGFR from sGFR. GFR estimated by abbreviated Modification of Diet in Renal Disease (MDRD) equation (aGFR) was evaluated as the criterion in selection of DPSM and SPSM. The condition that DPSM could be substituted by SPSM in GFR measurement was given.
When tGFR >or= 30 mL/(minx1.73 m(2)), all of the sGFR were significantly correlated with tGFR. Among them, Watson modified Christensen and Groth's equation at sample time=240 min tended to be the most accurate (r=0.977, RMSE=10.91), and tGFR could be predicted from sGFR using the equation: Predicted tGFR [mL/(minx1.73 m(2))]=7.755 4+0.789 3xsGFR+0.002 4 xsGFR2 (n=297, r2=0.959 1, P<0.001). When aGFR was less than 50 mL/(minx1.73 m(2)), the diagnostic sensitivity of tGFR<30 mL/(minx1.73 m(2)) was 94.7%, and recommended as the criterion in selection of DPSM and SPSM.
When aGFR >or=50 mL/(minx1.73 m(2)), DPSM can be substituted by SPSM in GFR measurement.