Evaluation of the Effect of Two Gadolinium-Containing Contrast-Enhancing Agents, Gadobutrol and Gadoxetate Disodium, on Colorimetric Calcium Determinations in Serum and Plasma

Objective: To determine the extent to which the gadolinium-containing contrast agents, gadobutrol (Gadovist) and gadoxetate disodium (Primovist/Eovist), interfere with the colorimetric measurement of calcium concentrations in serum and plasma. Materials and Methods: Gadobutrol and gadoxetate disodium were added in various concentrations to serum and plasma from healthy volunteers; the calcium concentration in these samples was then measured by standard colorimetry methods and atomic absorption. Results: At clinically relevant concentrations, neither gadobutrol nor gadoxetate disodium influenced the results of the calcium measurement in serum or plasma. Only at the highest concentrations tested (50 mM gadobutrol; 25 mM gadoxetate disodium), an effect was seen in some cases. Results were confirmed by atomic absorption spectroscopy as the reference method. Conclusions: At clinically relevant concentrations, gadobutrol and gadoxetate disodium did not interfere with standard colorimetric methods for calcium determination.