Some patients may develop adverse reactions or side effects from substances called radiocontrast media. These substances are given to patients before an X-ray or computerized tomography (CT) scan. The substances improve the visibility of the internal organs, allowing healthcare providers to detect cancerous tumors and abnormal growths.
There are two main types of contrast media: barium sulfate and iodine. Barium sulfate is a white powder that is mixed with water. The agent is most often used to help healthcare providers see the internal organs of the digestive tract, such as the intestines. Barium sulfate is usually swallowed or administered as an enema. The substance will be excreted from the body in the feces.
Iodine-based radiocontrast media are can be used almost anywhere in the body. They are typically injected into veins, but they may also be injected into an artery, injected into the spine, or injected into the abdomen.
Iodine may be formulated as either an ionic compound or an organic (non-ionic) compound. Ionic compounds were developed first, and they are still widely used today. Although ionic compounds are more likely to cause side effects than organic compounds, adverse reactions are uncommon. Organic compounds have fewer side effects because, unlike ionic compounds, they do not separate into smaller particles once they dissolve in water. This means the concentration of particles dissolved in a fluid, also called osmolality, is one-half that of ionic agents. Substances with higher osmolality are more likely to cause adverse reactions.
Adverse reactions from radiocontrast media are rare and symptoms can range from mild to life threatening. Serious side effects include an anaphylaxis-like reaction and kidney damage. Normally, anaphylaxis reactions are allergic reactions that involve the immune system. When anaphylaxis reactions occur in response to radiocontrast media, the immune system is not involved. Therefore, it is not considered true anaphylaxis. Kidney damage may occur because the kidneys must break down the radiocontrast media.
Radiocontrast media should not be given to patients who have experienced adverse reactions in the past because they have an increased risk of experiencing reactions in the future.
Treatment for adverse reactions depends on the type and severity of symptoms. Commonly used treatments include electrical cardioversion, epinephrine, hemodialysis, isotonic fluid, and supplemental oxygen.
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