Abstract for presentation at 38th Annual Scientific Meeting of the Australian and New Zealand Society of Nuclear Medicine 2008

Aim:
Simple measurement of serum creatinine and the estimated glomerular filtration rate (GFR) using various prediction equations have been the mainstay of renal function assessment at bedside. This study compares, correlates and analyses the validity of these equations in voluntary renal donors, with the gamma camera method for GFR estimation taken as the reference.

Methods:
37 voluntary renal donors (29 females and 8 males; Age range: 25-65years) who had undergone Tc-99m-diethylenetriaminepentaaceticacid (Tc-99m-DTPA) renogram (using a single head gamma camera) for GFR estimation (DTPA-GFR) were enrolled. The donors were referred during the period March 2005 to November 2006.
GFR was also estimated using the following prediction equations for these 37 donors:
a) Cockcroft-Gault equation (a commonly used surrogate marker for actual creatinine clearance) corrected for GFR (CG-GFR)
GFR(ml/min) = 140–age(years)xweight(kg)xConstantx0.84
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72xSr. Creatinine(mg/dL)
Constant-1(if male); 0.85(if female)
b) Modification of Diet in Renal Disease (MDRD) formula
GFR(ml/min) = 186x(Sr. Creatinine in mg/dL)^-1.154x(Age in years)^-0.203xConstant(1 if male; 0.742 if female)
All the GFR values obtained were normalized for the standard body surface area of 1.73m².

Results:
Mean DTPA-GFR was 86.6 ml/min, with a range of 47.6–149.5 ml/min. Pearson’s correlation coefficient between DTPA-GFR and estimated GFR (prediction equation GFRs) varied from 0.29-0.31.

Conclusion:
Our results suggest that there is a poor correlation between DTPA-GFR and GFR values obtained from prediction equations. Hence, these prediction equations for GFR estimation cannot be recommended for routine use, as an alternate to GFR estimation by gamma camera method, in voluntary renal donors.