Automated colorimetric gadolinium assay for verification of clearance and estimation of glomerular filtration rate

Background: NSF (nephrogenic systemic fibrosis) is a potentially serious adverse effect for renal patients undergoing MRI (magnetic resonance imaging) procedures using gadolinium-containing contrast agents. There is therefore a need to verify clearance of these agents and to confirm appropriate renal status of patients treated with these drugs. Methods. Serum samples from canine and feline subjects dosed with 0.1 mmol/kg of gadolinium agent, or from spiked samples were assayed for gadopentetate (Magnevist (R)), gadodiamide (Omniscan (R)) or gadoversetamide (OptiMARK (R)) using a new dye reagent on the Olympus AU400. Accuracy was verified by ICP-MS. Results: The reportable dynamic range is 3-600 mu mol/l Gd. Split serum samples from animals dosed with 0.1 mmol/kg of gadopentetate ranged from 7-458 mu mol/l Gd: y=1.121x+0.267, r=0.996, for the Olympus method as a function of Gd measurement by ICP-MS. Between-day imprecision was 1.3% CV-3.6% CV for samples ranging from 12-400 mu mol/l Gd. Conclusions: The assay is useful to verify the clearance of gadoliniurn and for evaluation of renal status by estimation of GFR using gadopentetate. (C) 2008 Elsevier B.V. All rights reserved.