A Newly Recognized DXA Confounder: The Potassium-Binding Medication Sodium Zirconium Cyclosilicate

Radiopacity of Sodium Zirconium Cyclosilicate in Computed Tomography: a case of a patient with Hyperkalemia and kidney disease

Sodium Zirconium Cyclosilicate (SZC) is commonly used for treating hyperkalemia because it sequesters gastrointestinal potassium ions, thereby reducing serum potassium levels. However, a less-discussed aspect of SZC is its radiopacity on x-ray-based imaging techniques. The European Medicines Agency (EMA) has only vaguely addressed this issue. Radiopaque substances like SZC can interfere with diagnostic imaging, creating challenges for clinicians and radiologists. We present the case of a 34-year-old Italian male to illustrate these concerns.

Radiopacity of sodium zirconium cyclosilicate on CT imaging

A patient who post-operatively develops hyperkalemia is treated with sodium zirconium cyclosilicate (Lokelma^®), a novel agent used for the treatment of non-life-threatening hyperkalemia with reduced side effects as compared with its predecessors. On CT imaging of the chest, abdomen, and pelvis, a radiopaque fluid is noticed despite the patient not having received any oral or intravenous contrast nor any medications or supplements that may appear radiopaque. Based on previous CT imaging of zirconium-based tooth implants and their radiopaque appearance on images, it is hypothesized that the sodium zirconium cyclosilicate that the patient was administered is the explanation of the radiopacity on CT imaging. We performed an in-vitro experiment to confirm that Lokelma is radiopaque to support our hypothesis. It is important to fully understand the differential of what may cause different appearances on imaging as well as to eliminate potential sources of artifact prior to imaging, or alternatively, to potentially be able to use medications with known radiopaque properties as alternatives to contrast agents.