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

BackgroundNSF (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.MethodsSerum samples from canine and feline subjects dosed with 0.1 mmol/kg of gadolinium agent, or from spiked samples were assayed for gadopentetate (Magnevist®), gadodiamide (Omniscan®) or gadoversetamide (OptiMARK®) using a new dye reagent on the Olympus AU400. Accuracy was verified by ICP-MS.ResultsThe reportable dynamic range is 3–600 µmol/l Gd. Split serum samples from animals dosed with 0.1 mmol/kg of gadopentetate ranged from 7–458 µmol/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 µmol/l Gd.ConclusionsThe assay is useful to verify the clearance of gadolinium and for evaluation of renal status by estimation of GFR using gadopentetate.