Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses

Walsh, D.M.; Royal, H.D.

Evaluation of a single injection of 99mTc-labeled diethylenetriaminepentaacetic acid for measuring glomerular filtration rate in horses

1992

Walsh, D.M. | Royal, H.D.

Glomerular filtration rate (GFR) was measured in 12 clinically normal horses, using the standard inulin clearance method, and values were compared with values for 2 methods, using a single rapid IV injection of (99m)Tc-labeled diethylenetriaminepentaacetic acid ((99m)Tc-DTPA). The first (99m)Tc-DTPA method used a 2-compartment model to calculate GFR blood clearance of the tracer. The second method used sequential digital gamma camera images of the kidneys to determine fractional accumulation of the total dose of the tracer in the kidneys (percentage of injected dose, gamma camera) from 0 to 10 minutes after radionuclide administration. Linear correlation among the 3 methods was determined. Mean (+/- SD) GFR, using the inulin clearance method, was 154.67 +/- 42.28 ml/min/100 kg of body weight. Mean GFR, using the 2-compartment blood clearance curve, was 146.92 +/- 27.49 ml/min/100 kg. Mean GFR, using percentage of injected dose (gamma camera method) was 154.7 +/- 22.00 ml/min/100 kg. The percentage of injected dose (gamma camera method) did not correlate significantly to the inulin clearance results. However, a significant (r = 0.666, P < 0.018) correlation was observed between the inulin method and the (99m)Tc-DTPA blood clearance method. Significant (P < 0.0001) difference also was observed in the split function of the equine kidneys, with GFR of the right kidney contributing 60.1 +/- 9.12% of the total function, as determined by (99m)Tc-DTPA gamma camera imaging. Because the (99m)Tc-DTPA blood clearance method does not require urine collection, it may be a more practical procedure to measure GFR in the horse.

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