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Introduction ⬇

A whole-body scan using 131I can identify functioning thyroid tissue throughout the body. It is useful to determine the presence of metastatic thyroid cancer and the amount and location of residual tissue after thyroidectomy. The scan is routinely performed in conjunction with thyroid therapy using 131I for thyroid carcinoma.

Procedure ⬆ ⬇

  1. Administer radionuclide orally in a capsule form.

  2. Perform scan 24–72 hours after administration of the radiopharmaceutical. Imaging may take as long as 2 hours to perform.

  3. Sometimes thyrotropin (TSH) is administered intravenously before the radionuclide is given. This stimulates any residual thyroid tissue and enhances 131I uptake.

  4. See Chapter 1 guidelines for safe, effective, informed intratest care.

Procedural Alert

  1. If possible, this test should be performed before any other radionuclide procedures 
and before use of anti-iodine contrast medium, surgical preparation, or other form of iodine.

  2. The test is most effective when endogenous TSH levels are high, so as to stimulate radionuclide uptake by metastatic neoplasms.

Clinical Implications ⬆ ⬇

Abnormal uptake of iodine reveals:

  1. Areas of extrathyroid tissue such as:

    1. Struma ovarii

    2. Substernal thyroid

    3. Sublingual thyroid

  2. Residual tissue after thyroidectomy

  3. Metastatic thyroid cancer

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain the purpose, procedure, benefits, and risks.

  2. Advise a woman of childbearing age that a pregnancy test will need to be performed before testing.

  3. Advise the patient that the imaging process may take several hours. If iodine allergies are suspected, observe the patient for possible reactions.

  4. Refer to standard NMI pretest precautions.

  5. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

Posttest Patient Care

  1. Refer to standard NMI posttest precautions.

  2. Review test results; report and record findings. Modify the nursing care plan as needed.

  3. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Reference Values ⬆

Normal

No functioning thyroid tissues outside of the thyroid gland