title: Renal and extrarenal clearance of 99mTc-MAG3: a comparison with 125I-OIH and 51Cr-EDTA in patients representing all levels of glomerular filtration rate.
abstract: . This investigation was undertaken in order to determine whether the clearance of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3) is more closely correlated to the clearance of iodine-125 orthoiodohippurate (125I-OIH) than to the clearance of chromium-51 ethylene diamine tetra-acetate (51Cr-EDTA) and whether there is a clinically significant extrarenal clearance of 99mTc-MAG3 . Fifty-one patients with a glomerular filtration rate (GFR) of 4-132ml/min were studied. After a simultaneous single injection of the three tracers, plasma clearance was measured from blood samples 0-5h post injection (p.i.) (0-24h in patients with GFR<15ml/min). Renal plasma clearance was measured 0-5h p.i. The ratio between the renal plasma clearance of 99mTc-MAG3 and 125I-OIH was 0.57. The ratio between the renal plasma clearance of 99mTc-MAG3 and 51Cr-EDTA was 2.57. The coefficient of variation (CV) of the 99mTc-MAG3/125I-OIH ratio was significantly smaller than the CV of the 99mTc-MAG3/51Cr-EDTA ratio (13.4% versus 31.2%). The corresponding plasma clearance ratios were 0.59 (CV=14.8%) and 2.48 (CV=27.0%). Plasma clearance overestimated renal plasma clearance by 7.0ml/min (5.4%) for 99mTc-MAG3 and by 4.1ml/min (8.4%) for 51Cr-EDTA. The difference in plasma and renal plasma clearance of 125I-OIH of 5.5ml/min did not reach statistical significance. Red blood cell binding of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 2.0%, 14.6% and 0.2%, respectively. Protein binding of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 86.3%, 61.1% and 5.9%, respectively. The volume of distribution of 99mTc-MAG3, 125I-OIH and 51Cr-EDTA was 16.3%, 27.0% and 19.4% of body weight. In conclusion, the clearances of 99mTc-MAG3 and 125I-OIH are more closely correlated than is the clearance of 99mTc-MAG3 with GFR. Extrarenal clearance of 99mTc-MAG3 is relatively smaller than extrarenal clearance of 51Cr-EDTA. Thus, plasma clearance of 99mTc-MAG3 can be used as a measure of renal tubular function.
authors.affiliation: Department of Clinical Physiology and Nuclear Medicine, Skejby University Hospital, Aarhus, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Rehling
authors.forename: B V
authors.initials: BV
authors.lastname: Nielsen
authors.forename: E B
authors.initials: EB
authors.lastname: Pedersen
authors.forename: L E
authors.initials: LE
authors.lastname: Nielsen
authors.forename: H E
authors.initials: HE
authors.lastname: Hansen
authors.forename: T
authors.initials: T
authors.lastname: Bacher
mesh_terms: D000328:Adult; D000368:Aged; D002860:Chromium Radioisotopes / Q000493:pharmacokinetics*; D004492:Edetic Acid / Q000493:pharmacokinetics*; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics*; D007465:Iodohippuric Acid / Q000493:pharmacokinetics*; D007668:Kidney / Q000000981:diagnostic imaging / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D011877:Radionuclide Imaging; D017263:Technetium Tc 99m Mertiatide / Q000493:pharmacokinetics*
chemical_list: D002860:Chromium Radioisotopes; D007457:Iodine Radioisotopes; D007465:Iodohippuric Acid; D017263:Technetium Tc 99m Mertiatide; D004492:Edetic Acid