Thrombocytopenia Induced by Iodinated Contrast Media: A Systematic Review

Abstract

Iodinated contrast media are routinely used in clinical practice for diagnostic and therapeutic purposes. Adverse effects of their administration have an incidence of 3 %, and mostly consist of mild skin allergic reactions, with severe reponses such as anaphylaxis representing only 0.22 %. Contrast-induced thrombocytopenia is an extremely rare, underdiagnosed condition that most often occurs after infusion of hyperosmolar contrast agents, with low-osmolarity compounds being less likely the trigger. We report a systematic review of this condition based on the currently available series of case reports (18), as well as the clinical course of the presentation and platelet count during episodes. The physiopathogenic mechanism remains unknown, although the presence of some immune-mediated process involving changes in platelet aggregation and activation is currently accepted. Platelet response is immediate (within a few hours after exposure to the contrast agent) and consists of a fall in platelet count to < 20 x 109/L, which returns to normal at day 3 or 4. Diagnostic criteria are based on those by George and Arnold, the latter more specific for drug-induced thrombocytopenia. No routine diagnostic laboratory tests are presently available to establish a definite diagnosis, and treatment usually consists of support measures to prevent complications from occurring, but steroids, immunoglobulins, plasma exchange and/or platelet transfusions may be used. Despite its low incidence, iodinated contrast-induced thrombocytopenia is a complication to consider that may cause severe thrombocytopenia after administration of iodinated contrast agent during some diagnostic test and/or angiography.