Gfr estimation using 99mTc dtpa gates method for assessment of early diabetic nephropathy - a comparison with 24-hour creatinine clearance

ABSTRACT

To correlate Gates glomerular filtration rate [GGFR] using technetium-99m diethylene triaminepentacetic acid [99mTc DTPA] with 24-hour creatinine clearance [CRCL] and to establish relationship with duration of diabetes in patients with early diabetic nephropathy. A cross-sectional comparative study carried out in Nuclear Medical Centre from Aug 2009 to Jan 2010 at Armed Forces Institute of Pathology [AFIP], Rawalpindi, Pakistan. A total of eighty three subjects were enrolled, who were divided into three groups; group 1 comprised 31 normotensive diabetics, group 2 had 37 hypertensive diabetics while group 3 had 15 normal subjects. The DTPA GFR and creatinine clearance in healthy subjects as well as diabetic patients were compared using the unpaired student's t-test. The linear association between GFR, creatinine clearance and disease duration was expressed by Pearson's correlation coefficient V along with their significance levels. Gates GFR showed hyperfiltration in normotensive diabetics [96.6 +/- 3.3 ml/min/1.73 m[2]], significantly [p<0.05] higher than controls [85.5 +/- 5 ml/min/1.73 m[2]], whereas hypertensive diabetics had a significantly lower [p<0.05] Gates GFR [76.8 +/- 3.7] than that of controls. Significant degree of correlation existed between GGFR and CRCL in hypertensive diabetics [p<0.05, r=0.716] and controls [r=0.546]. Gates GFR also showed good correlation with duration of diabetes in both diabetic groups as compared to that of CRCL. GGFR also correlated well with duration of hypertension 0.37 [0.31-0.43] as compared to CRCL 0.155 [0.15-0.16] in all groups. The 99mTc-DTPA clearance correlates significantly with 24-hour creatinine clearance as well as with disease duration and can provide a simple and convenient index of kidney function in patients of early diabetic nephropathy