Which gadolinium-based contrast agents interfere with the colorimetric assays for calcium testing?

Updated: Aug 08, 2019
  • Author: Manish Suneja, MD, FASN, FACP; Chief Editor: Vecihi Batuman, MD, FASN  more...
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Gadodiamide and gadoversetamide, which are gadolinium-based contrast agents used in magnetic resonance imaging and angiography, may interfere with the colorimetric assays for calcium that are frequently used in hospital laboratories. This effect is not observed with other gadolinium-based agents: dimeglumine gadopentetate, gadoteridol, or gadoterate meglumine.

The interaction can result in a marked reduction in the measured calcium concentration of as much as 6 mg/dL if a blood sample is obtained soon after the imaging study. This effect is rapidly reversible as the gadolinium is excreted in the urine, and the patient has no symptoms or signs of hypocalcemia.

Awareness of this phenomenon is particularly important in patients with renal insufficiency who may retain the contrast agent for prolonged periods. There is no reason to treat this type of hypocalcemia. [42, 43, 44]

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