Filtration fraction and its implications for radionuclide renography using diethylenetriaminepentaacetic acid and mercaptoacetyltriglycine.
OBJECTIVE
Glomerular filtration rate (GFR) and effective renal plasma flow (ERPF) were determined in 92 patients to calculate filtration fraction (GFR/EFPR) and evaluate its change in renal diseases. This information was used as the rationale for a renogram protocol using DTPA (to estimate GFR) and MAG3 (to produce images and curves).


METHODS
Individual kidney GFR and ERPF were determined by gamma camera techniques using Tc-99m DTPA and I-131 OIH. Two hundred sixty-one determinations were performed in 92 patients who in turn were grouped into 4 categories: normal, obstruction, renal vascular disease, and chronic insufficiency.


RESULTS
Mean filtration fractions in normal patients and those with obstruction were similar (0.16 and 0.15, respectively), whereas they were lower in renal vascular disease (0.11) and chronic renal insufficiency (0.08). Low filtration fraction indicates disproportionate loss of GFR compared with ERPF and was the pattern observed with advancing renal disease in most patients. The exception was ATN or contrast nephropathy when filtration fraction was increased (0.22) as a result of disproportionate loss of ERPF compared with GFR.


CONCLUSIONS
OIH is no longer available in the United States, and MAG3 is now used as the renal tubular agent in renography. Clearance of MAG3 does not directly measure ERPF, but this might not be a significant loss in clinical practice if GFR is measured during renography because it is more adversely affected by renal disease than ERPF (with the exception of ATN and contrast nephropathy). Accordingly, a renogram protocol is presented for the combined use of DTPA and MAG3 resulting in GFR estimation (from DTPA) while yielding superior renal images and renogram curves from MAG3.
Gates
Gary F
GF
Nuclear Medicine Department, Providence St. Vincent Medical Center, Portland, OR 97225, USA. garry_gates@providence.org
D000293:Adolescent; D000328:Adult; D000367:Age Factors; D000368:Aged; D000375:Aging; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007668:Kidney / Q000098:blood supply* / Q000000981:diagnostic imaging*; D007674:Kidney Diseases / Q000000981:diagnostic imaging*; D007677:Kidney Function Tests / Q000379:methods; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D019275:Radiopharmaceuticals; D012079:Renal Circulation; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D012737:Sex Factors; D017263:Technetium Tc 99m Mertiatide; D016284:Technetium Tc 99m Pentetate
D019275:Radiopharmaceuticals; D017263:Technetium Tc 99m Mertiatide; D016284:Technetium Tc 99m Pentetate