Quantitative and qualitative scintigraphic measurement of renal function in dogs exposed to toxic doses of gentamicin

Five, 3-month-old mongrel dogs weighing between 4.5 to 5.5 kg were studied to evaluate and compare the efficiency of Tc-99m-DTPA, Tc-99m-MAG(3), and T c-99m-DMSA in detecting gentamicin-induced renal tubular injury. After base line renograms using all three methods, all dogs received daily intramuscul ar injections of gentamicin at a dose of 30-45 mg/kg. Additional studies we re obtained after a cumulative dose of 450, 1,575, and 2,250 mg of gentamic in was reached. Glomerular filtration rate (GFR), effective renal plasma fl ow (ERPF), and percentage of total renal uptake measurements were calculate d. Baseline and post-gentamicin injection blood urea nitrogen (BUN) and ser um creatinine values were determined. A Duncan test revealed significant re nal function impairment at 450 mgs of cumulated gentamicin with Tc-99m-DMSA and at 1,575 mgs of cumulated gentamicin for Tc-99m-DTPA and Tc-99m-MAG(3) . There was no correlation between BUN and serum creatinine values when com pared to gentamicin (p > 0.05). The images obtained with Tc-99m-MAG(3) were of better quality than those obtained with Tc-99m-DTPA even under severe r enal dysfunction. Percentage of Tc-99m-DMSA uptake indicated renal damage, before than GFR and ERPF. BUN and serum creatinine measurements were poor i ndicators of gentamicin-induced renal failure.