A physiologic approach to renal scintigraphy. Application to evaluation of hypertension

The aim of this study was to define the use of the triple radiopharmaceutical renal study (TRRS) for renal scintigraphy as a physiological tool for renal evaluation, and to determine if the sensitivity and/or specificity of a renal study for the diagnosis of renovascular hypertension (RVH) could be improved by the combination of three radiopharmaceuticals (i.e., I-131 OIH, Tc-99m DTPA, and Tc-99m glucoheptonate). One hundred ninety-five patients with suspected RVH underwent TRRS, standard Tc-99m DTPA renal studies, and renal angiography. One hundred eighty-nine patients were hypertensive and ischemic nephropathy was suspected in six. Ninety-one, including three patients with ischemic nephropathy, had a renal artery stenosis of 70% or more (66 unilateral, 25 bilateral). Effective renal plasma flow (ERPF), glomerular filtration rate (GFR) (from plasma clearance of I-131 OIH and Tc-99m DTPA), and geometric renal masses (from Tc-99m glucoheptonate study) were compared to normal values corrected for body surface, to determine the severity of renal dysfunction. For the TRSS, RVH criteria included: 1) differential Tc-99m DTPA function minus differential Tc-99m glucoheptonate function of affected kidney ( < -5% or > 5%) and 2) functional parameters: ERPF = 1.6-2.0 ml/g/minute, GFR = 0.25-0.4 ml/g/minute, and filtration fraction (i.e., GFR/ERPF = 0.15-0.20) on the affected side.