Evaluation of the Influence of Kidney Depth in GFR with Radionuclide Renal Scintigraphy

To evaluate the effect of kidney depth in calculating GFR with radionuclide renal scintigraphy,482 patients with chronic kidney disease(CKD) were selected.GFR were estimated simultaneously using three methods: modified Gate's method(gGFR);Gate's method with the verify formulae of depth(v-gGFR);dual plasma sampling method(rGFR).Using rGFR as the reference method,gGFR and v-gGFR were compared with rGFR.In v-gGFR,instead of Tonnesen's formula,which was used to estimate the renal depth in Gate's method,we adopted the renal depth formula obtained in our previous study: right kidney depth(cm)=15.449×(weight/height)+0.009637×age+0.782;left kidney depth(cm)=16.772×(weight/height)+0.01025×age+0.224(weight,kg;height,cm).All statistics were performed using SPSS 10.0 and P0.05 indicates statistical significance.Quantitative variables were described as x-±s or median.The estimated gGFR and v-gGFR were compared using Bland-Altman analysis.The spearman correlation and linear regression were used to describe the relationship between gGFR/v-gGFR and rGFR.The results showed that both gGFR and v-gGFR were correlated well with rGFR(r=0.75,P0.001;r=0.81,P0.001).The difference and absolute difference between v-gGFR and rGFR were siginificantly less than those between gGFR and rGFR.For gGFR,the 15%,30% and 50% accuracies were 32.4%,56.0% and 79.1%,respectively;for v-gGFR,the corresponding accuracy rose to 45.0%,74.5% and 89.9%,respectively.In this research,the GFR was obtained by the new formula of kidney depth was more accurate than GFR estimated by tradional radionuclide renal scintigraphy.