Interference of gadolinium-containing contrast-enhancing agents with colorimetric calcium laboratory testing.

OBJECTIVES

The purpose of this study was to evaluate the extent to which various commercially available gadolinium-containing contrast-enhancing (CE) agents can interfere with the measurement of calcium levels by currently used laboratory methods, suggesting (spurious) hypocalcemia or hypercalcemia with a potential risk for the patient.

MATERIALS AND

METHODS

Serum and plasma from healthy volunteers were spiked with various concentrations of 4 marketed CE agents. The calcium concentration was measured by widely used laboratory methods: the colorimetric systems Cobas Mira and Vitros 950 analyzer.

RESULTS

The measurement of calcium in serum and in plasma was not affected by the presence of gadopentetate dimeglumine (Magnevist, Schering AG, Berlin, Germany) or gadobenate dimeglumine (MultiHance, Bracco-Byk Gulden, Constance, Switzerland) in clinically relevant concentrations (up to 5 mM CE agent). Gadodiamide (Omniscan, Amersham Health, Cork, Ireland) and gadoversetamide (OptiMARK, Mallinckrodt, St. Louis, MO) did produce noticeable-and therefore potentially misleading-effects at these concentrations.

CONCLUSIONS

The study demonstrates that gadopentetate dimeglumine and gadobenate dimeglumine generate no interference with colorimetric methods for calcium determination, whereas strong interference was shown for gadodiamide and gadoversetamide under clinically relevant conditions.