Evaluation Of The Application Of ^99mTc-DTPA Renography And Glomerular Filtration Rate Estimation Equations

Objective:To evaluate the application of ^99mTc-DTPA renal dynamic imaging,CG equation and MDRD equations in the determination of GFR ,in order to find a good method of glomerular filtration rate.Mehtods:54 patients with chronic kidney disease(CKD) were selected.The CKD were diagosed according to K/DOQI guideline. 5 mci (185MBq)/1ml dose of ^99mTc-DTPA was injected as a bolus in an antecvbital vein.Renal scinitigraphic images were collected immediately and the images were processed under standard procedure (Gates method) to obtain GFR.Four ml of blood was withdrawn 2h and 4h psstinjection respectively and radioactivity of 1ml plasma was measured.GFR was calculated by the formula of two-sample method. And used the CG equations MDRD equations to estimate the GFR.All the results were standardized by body surface according to the tGFR and CKD stages,the patients were devided into 5 subgroups:1.GFR≥90ml/min/1.73m2;2.GFR60-89ml/min/1.73m2; 3.GFR 30-59ml/min/1.73m2;4.GFR15-29ml/min/1.73m2;5.GFR<15ml/min/1.73m2.The correlation between gGFR and tGFR,cGFR and tGFR,mGFR and tGFR,aGFR and tGFR,eGFR and tGFR were analysied respectively .Results:54 Patients with CKD. Male 29.female 25.The average age is 54.25±19.74. (1)Cr,Bun showed greater correlation with tGFR. (r=0.911 p<0.01). In different CKD stages the correlationship were poor. (p<0.001). (2)gGFR and tGFR showed greater correlation.(r=0.911 p<0.01).In CKD stages 1-2, gGFR was lower than tGFR,the higher tGFR, the greater the differences. In CKD stages 3to 5 gGFR was higher than tGFR, the lower the tGFR ,the greater the differences(P<0.01);The degree of the deviation was different between gGFR and tGFR (P<0.01).The degree of deviation was lower in CKD 1-2 than 3-5. (3) cGFR and tGFR showed greater correlation.(r=0.911 p<0.01).In CKD stages 1-5, cGFR was lower than tGFR,the lower the tGFR, the greater the differences.(P<0.01); In different CKD stages ,the degree of the deviation was different between cGFR and tGFR (P<0.01). The degree of deviation was higher in CKD 1-2 than 3-5.(4) mGFR and tGFR showed greater correlation.(r=0.97 p < 0.01).In CKD stages 1-3, mGFR was lower than tGFR,the higher the tGFR, the greater the difference. In CKD stages 4-5, mGFR was higher than tGFR,the lower the tGFR, the greater the differences.(P<0.01); In different CKD stages ,the degree of the deviation was different between mGFR and tGFR (P<0.01). The degree of deviation was higher in CKD 1-2 than 3-5. (5) aGFR and tGFR showed greater correlation. (r=0.987 p<0.01).In CKD stages 1-3, aGFR was lower than tGFR,the higher the tGFR, the greater the differences. In CKD stages 4-5, aGFR was higher than tGFR,the lower the tGFR, the smaller the differences. (P<0.01); In different CKD stages ,the degree of the deviation was different between mGFR and tGFR (P<0.01). The degree of deviation was higher in CKD 1-2 than 3-5. (6)eGFR and tGFR showed greater correlation.( r=0.975 p=0.048).In different CKD stages there was no significant differences(p>0.05) and the deviation was different, but no significant differences(p>0.05).Conclsions: (1)The accuracy and sensitivity of Cr,Bun are poor and not good methods for evaluating GFR in clinical practice. GFR obtained by renal dynamic imaging is not reliable for identifying the changes in renal functionandnot well with GFR obtained by two-samplemethod. (2) Compared with tGFR ,the mGFR,aGFR,cGFR show significantly difference and could not estimate GFR accurately.The modified MDRD equation based on Chinese CKD patients manifest significantly advantages in different CKD stages, but more samples are needed further to prove its value.