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), gadodiamide (Omniscan) or gadoversetamide (OptiMARK) using a new dye reagent on the Olympus AU400. Accuracy was verified by ICP-MS.


RESULTS
The reportable dynamic range is 3-600 micromol/l Gd. Split serum samples from animals dosed with 0.1 mmol/kg of gadopentetate ranged from 7-458 micromol/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 micromol/l Gd.


CONCLUSIONS
The assay is useful to verify the clearance of gadolinium and for evaluation of renal status by estimation of GFR using gadopentetate.
IDEXX Laboratories, Inc., One IDEXX Drive, Westbrook, ME 04092, USA.
Ralph A
RA
Magnotti
Jodi L
JL
Connell
Peter M
PM
Marietta
D000818:Animals; D001331:Automation; D001681:Biological Assay; D002415:Cats; D003124:Colorimetry / Q000379:methods*; D003287:Contrast Media / Q000009:adverse effects / Q000493:pharmacokinetics*; D005682:Gadolinium / Q000009:adverse effects / Q000493:pharmacokinetics*; D019786:Gadolinium DTPA; D005919:Glomerular Filtration Rate / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D013058:Mass Spectrometry; D009942:Organometallic Compounds; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity
D003287:Contrast Media; D009942:Organometallic Compounds; C064925:gadodiamide; D005682:Gadolinium; D019786:Gadolinium DTPA; C112666:gadoversetamide