GFR ESTIMATION USING 99mTc DTPA GATES METHOD FOR ASSESSMENT OF EARLY DIABETIC NEPHROPATHY – A COMPARISON WITH 24-HOUR CREATININE CLEARANCE

Diabetic Nephropathy

Abstract

Objective: 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.
Study Design: 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.
Patients and Methods: 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 'r' along with their significance levels.
Results: Gates GFR showed hyperfiltration in normotensive diabetics (96.6 ± 3.3 ml/min/1.73 m2), significantly (p<0.05) higher than controls (85.5 ± 5 ml/min/1.73 m2), 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.
Conclusions: 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.