Radiopaque Agents (Diagnostic)

Before Having This Test

In deciding to use a diagnostic test, any risks of the test must be weighed against the good it will do. This is a decision you and your doctor will make. Also, test results may be affected by other things. For radiopaque agents, the following should be considered:

Allergies - Tell your doctor if you have ever had any unusual or allergic reaction to iodine, to products containing iodine (for example, iodine-containing foods such as seafood, cabbage, kale, rape [turnip-like vegetable], turnips, or iodized salt), or to any radiopaque agent. Also tell your doctor if you are allergic to any other substance, such as sulfites or other preservatives.

Pregnancy - Studies have not been done in humans with most of the radiopaque agents. However, iohexol, iopamidol, iothalamate, ioversol, ioxaglate, and metrizamide have not been shown to cause birth defects or other problems in animal studies. Some of the radiopaque agents, such as diatrizoates have, on rare occasions, caused hypothyroidism (underactive thyroid) in the baby when they were taken late in the pregnancy. Also, x-rays of the abdomen are usually not recommended during pregnancy. This is to avoid exposing the fetus to radiation. Be sure you have discussed this with your doctor.

Breast-feeding - Although some of these radiopaque agents pass into the breast milk, they have not been shown to cause problems in nursing babies. However, it may be necessary for you to stop breast-feeding temporarily after receiving a radiopaque agent. Be sure you have discussed this with your doctor.

Children - Children, especially those with other medical problems, may be especially sensitive to the effects of radiopaque agents. This may increase the chance of side effects.

Older adults - Elderly people are especially sensitive to the effects of radiopaque agents. This may increase the chance of side effects.

Other medical problems - The presence of other medical problems may affect the use of radiopaque agents. Make sure you tell your doctor if you have any other medical problems, especially:

• Asthma, hay fever, or other allergies (history of) - If you have a history of these conditions, the risk of having a reaction, such as an allergic reaction to the radiopaque agent, is greater

• Diabetes mellitus (sugar diabetes) - There is a greater risk of having kidney problems

• High blood pressure (severe) or
• Pheochromocytoma (PCC) - Injection of the radiopaque agent may cause a dangerous rise in blood pressure

• Kidney disease (severe) - More serious kidney problems may develop; also, the radiopaque agent may build up in the body and cause side effects

• Liver disease - The radiopaque agent may build up in the body and cause side effects

• Multiple myeloma (bone cancer) - Serious kidney problems may develop in patients with this condition

• Overactive thyroid - A sudden increase in symptoms, such as fast heartbeat or palpitations, unusual tiredness or weakness, nervousness, excessive sweating, or muscle weakness may occur

• Sickle cell disease - The radiopaque agent may promote the formation of abnormal blood cells

Preparation for This Test

Your doctor may have special instructions for you in preparation for your test. He or she might prescribe a special diet or use of a laxative, depending on the type of test. If you have not received such instructions or if you do not understand them, check with your doctor in advance.

For some tests your doctor may tell you not to eat for several hours before having the test. This is to prevent any food from coming back up and entering your lungs during the test. You may be allowed to drink small amounts of clear liquids; however, check first with your doctor.