Radiopharmaceuticals (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 radiopharmaceuticals, the following should be considered:

Allergies - If you will be receiving albumin in the form of radioiodinated albumin, technetium Tc 99m albumin aggregated, technetium Tc 99m albumin colloid, or technetium Tc 99m albumin for your test, tell your doctor if you have ever had any unusual or allergic reaction to products containing human serum albumin. Also tell your doctor if you are allergic to any other substance, such as foods, preservatives, or dyes.

Pregnancy - Radiopharmaceuticals usually are not recommended for use during pregnancy. This is to avoid exposing the fetus to radiation. Some radiopharmaceuticals may be used for diagnostic tests in pregnant women, but it is necessary to inform your doctor if you are pregnant so the doctor may reduce the radiation dose to the baby. This is especially important with radiopharmaceuticals that contain radioactive iodine, which can go to the baby's thyroid gland and, in high enough amounts, may cause thyroid damage. Be sure you have discussed this with your doctor.

Breast-feeding - Some radiopharmaceuticals pass into the breast milk and may expose the baby to radiation. If you must receive a radiopharmaceutical, it may be necessary for you to stop breast-feeding for some time after receiving it. Be sure you have discussed this with your doctor.

Children - For most radiopharmaceuticals, the amount of radiation used for a diagnostic test is very low and considered safe. However, be sure you have discussed with your doctor the benefit versus the risk of exposing your child to radiation.

Older adults - Many medicines have not been studied specifically in older people. Therefore, it may not be known whether they work exactly the same way they do in younger adults or if they cause different side effects or problems in older people. Although there is no specific information comparing use of most radiopharmaceuticals in the elderly with use in other age groups, problems would not be expected to occur. However, it is a good idea to check with your doctor if you notice any unusual effects after receiving a radiopharmaceutical.

Other medicines - Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are going to receive a radiopharmaceutical, it is especially important that your doctor know if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.

In addition, if you will be receiving radioactive iodine (sodium iodide I 123, sodium iodide I 131) or sodium pertechnetate Tc 99m for a thyroid test, it is especially important that your doctor know if you have been taking iodine through other medicine or foods. For example, the results of your test may be affected if:

• You are taking iodine-containing medicines, including certain multivitamins and cough syrups.

• You eat large amounts of iodine-containing foods, such as iodized salt, seafood, cabbage, kale, rape (turnip-like vegetable), or turnips.

• You have had an x-ray test recently for which you were given a special dye that contained iodine.

Other medical problems - The presence of other medical problems may affect the use of radiopharmaceuticals. Make sure you tell your doctor if you have any other medical problems.

Preparation for This Test

The nuclear medicine doctor may have special instructions for you in preparation for your test. For example, before some tests you must fast for several hours, or the results of the test may be affected. For other tests you should drink plenty of liquids. If you do not understand the instructions you receive or if you have not received any instructions, check with the nuclear medicine doctor in advance.