Procedure Guideline for Therapy of Thyroid Disease with 131Iodine
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PROCEDURE GUIDELINES Procedure Guideline for Therapy of Thyroid Disease with 131Iodine Donald A. Meier, MD1; David R. Brill, MD2; David V. Becker, MD3; Susan E.M. Clarke, MD4; Edward B. Silberstein, MD5; Henry D. Royal, MD6; and Helena R. Balon, MD1 1William Beaumont Hospital, Royal Oak, Michigan; 2Chambersburg Hospital, Chambersburg, Pennsylvania; 3New York Hospital Cornell Medical Center, New York, New York; 4Guys Hospital, London, United Kingdom; 5University of Cincinnati Hospital, Cincinnati, Ohio; 6Mallinckrodt Institute of Radiology, St. Louis, Missouri Licensure to possess 131I and regulations regarding the Key Words: 131Iodine therapy; thyroid cancer; thyroid disease; release of patients treated with radioiodine vary from juris- hyperthyroidism diction to jurisdiction. Physicians engaged in therapy with J Nucl Med 2002; 43:856–861 131I must be knowledgeable about and in compliance with all applicable laws and regulations. The facility in which treatment is performed must have PART I: PURPOSE appropriate personnel, radiation safety equipment, and pro- cedures available for waste handling and disposal, monitor- The purpose of this guideline is to assist nuclear medicine ing personnel for accidental contamination, and controlling practitioners in evaluating patients for therapy with 131I spread of volatilized 131I. (sodium iodide) for benign or malignant conditions of the thyroid gland, performing this treatment, understanding and Definitions evaluating the sequelae of therapy, and reporting the results of therapy. ● 131Iodine is a -emitting radionuclide with a physical half-life of 8.1 d, a principal ␥-ray of 364 KeV, and a PART II: BACKGROUND INFORMATION AND principal -particle with a maximum energy of 0.61 DEFINITIONS MeV, an average energy of 0.192 MeV, and a range in Oral administration of 131I has been a commonly ac- tissue of 0.8 mm. ● 131 cepted procedure for treatment of benign and malignant Therapy means the oral administration of Iasso- conditions of the thyroid since the 1940s. Physicians dium iodide. ● responsible for treating such patients should have an Benign conditions include Graves’ disease (toxic dif- understanding of the clinical pathophysiology and natural fuse goiter), toxic or nontoxic nodular goiter, and au- history of the disease processes, should be familiar with tonomously functioning toxic or nontoxic nodules. ● alternate forms of therapy, and should be able to collab- Malignant conditions include thyroid cancer that is orate closely with other physicians involved in the man- sufficiently differentiated to be able to synthesize thy- agement of the patient’s condition. The treating physician roglobulin and, in most cases, accumulate radioiodine. should either see patients in consultation with the physi- cian assuming overall management of the patient’s con- PART III: COMMON INDICATIONS dition or be prepared to assume that role. In the United A. Benign Conditions States, the treating physician should be board certified in 131 Nuclear Medicine, Radiology, or Radiation Oncology, or ● Hyperthyroidism. I may be indicated for the treat- be able to document equivalent training, competency, and ment of Graves’ disease, toxic multinodular goiter, experience in the safe use and administration of thera- or toxic autonomously functioning thyroid nodules. 131 peutic amounts of 131I. In Europe, the treating physician ● Nontoxic multinodular/diffuse goiter. I therapy should be board certified in Nuclear Medicine or Radia- has been used successfully to diminish the size of tion Oncology. nontoxic multinodular/diffuse goiter. B. Thyroid Cancer For correspondence or reprints contact: Donald A. Meier, MD, Associated ● 131I therapy has been used for postoperative ablation Endocrinologists, P.C., 6900 Orchard Lake Rd., Suite 203, West Bloomfield, MI 48322. of thyroid remnants after thyroidectomy. E-mail: [email protected] ● 131I therapy has been used to treat residual thyroid 856 THE JOURNAL OF NUCLEAR MEDICINE • Vol. 43 • No. 6 • June 2002 cancer and metastatic disease after partial or com- cause radiation thyroiditis with release of plete thyroidectomy. stored thyroid hormone into the circulation, resulting in occasional worsening of hyper- PART IV: PROCEDURE thyroidism and, rarely, precipitation of thy- roid storm. This is more likely to occur in A. Patient Preparation patients with large, iodine-avid multinodular 1. For All Patients glands who are given larger amounts of 131I. Accordingly, elderly patients and patients a. All patients must discontinue use of iodide- with significant preexisting heart disease, se- containing preparations, iodine supplements, vere systemic illness, or debility may benefit thyroid hormones, and other medications that from pretreatment with ATD. The ATD could potentially affect the ability of thyroid needs to be discontinued for at least 3 d tissue to accumulate iodide for a sufficient time before the radioiodine therapy is given. The before contemplated therapy (Table 1). ATD can be resumed 2–3 d after treatment b. The treating physician must explain the proce- with 131I. Some experts recommend admin- dure, treatment, complications, side effects, istering a larger amount of 131I in patients therapeutic alternatives, and expected outcome who have been pretreated with ATD. Treat- to the patient. Written information should be ment with -blockers can be helpful for provided to the patient.  c. The treating physician must obtain written in- symptomatic control. -Blockers need not be 131 formed consent before therapy. discontinued before treatment with I. c. The consent form should include the following 2. For Therapy of Hyperthyroidism and Nontoxic items specific for the therapy of hyperthyroid- Multinodular Goiter ism: a. The results from recent measurements of thy- ● More than one 131I treatment may be nec- roid hormone levels (free T4, free T3) and essary. thyroid stimulating hormone (TSH) should be ● The risk of eventual hypothyroidism is available and reviewed. The avidity of the thy- high, especially after treatment of roid gland for iodide must be established. This Graves’ disease, and lifelong daily inges- can be accomplished quantitatively using a re- tion of a thyroid hormone tablet would cent radioiodine uptake (RAIU), or qualita- then be necessary. tively using a thyroid scan. These procedures ● Long-term follow-up will be necessary. will differentiate silent thyroiditis and thyro- ● Ophthalmopathy may worsen or develop toxicosis factitia from other forms of hyperthy- after 131I therapy. roidism. ● Rarely, there can be transient neck sore- b. Pretreatment of selected patients with anti- ness or exacerbation of hyperthyroid thyroid drugs (ATD) to deplete thyroid hor- symptoms secondary to radiation thyroid- mone stores may be helpful. 131I therapy can itis. TABLE 1 Drug Interactions Type of medication Recommended time of withdrawal Antithyroid medication (e.g., propylthiouracil, methimazole, 3 d for antithyroid drugs carbimazole) and multivitamins 7 d for multivitamins* Natural or synthetic thyroid hormone (e.g., thyroxine, triiodothyronine) 2 wk for triiodothyronine† 4–6 wk for thyroxine† Expectorants, kelp, agar, carageen, Lugol’s solution, potassium iodide 2–3 wk, depending on iodide content* solution (“SSKI”) Topical iodine (e.g., surgical skin preparation) 2–3 wk* Radiographic contrast agents Intravenous (water soluble) 3–4 wk (assuming normal renal function) Lipophilic agents (rarely used) Ͼ1mo Amiodarone 3–6 months or longer *These time intervals relate to hyperthyroid patients. For thyroid cancer patients, a 6-wk time interval is recommended. †These times apply only to thyroid cancer patients. PROCEDURE GUIDELINE: 131ITHERAPY FOR THYROID • Meier et al. 857 3. For Therapy of Thyroid Cancer rent thyroid cancer and may be an indication a. Thyroid hormone medications must be with- for radioiodine therapy even in the absence of held for a time sufficient to permit an adequate discernible activity following a diagnostic dose 131 rise in TSH (Ͼ30 IU/ml). This is at least 2 of I. An elevated serum thyroglobulin does wk for triiodothyronine (T3) and 4 to 6 wk for not guarantee iodine avidity of the tumor. thyroxine (T4). TSH may not rise to this level e. A written informed consent form must be ob- if a large volume of functioning tissue remains. tained and could include the following items Recombinant human TSH is not currently ap- specific for the therapy of thyroid cancer: proved in the United States for use in 131I ● The purpose of the treatment is to destroy therapy, although there is FDA approval for normal and cancerous thyroid tissue. use in diagnostic testing. Other normal tissues may also be af- b. For patients receiving an ablative dose or treat- fected. ment dose of radioiodine following a partial or ● More than one 131I treatment may be nec- complete thyroidectomy for thyroid cancer, the essary. results from a recent measurement of TSH and ● Early side effects may include nausea, the operative and histology reports should be occasional vomiting, pain and tenderness available and reviewed. A baseline serum thy- in the salivary glands, loss of saliva or roglobulin should be obtained in the hypothy- taste, neck pain and swelling if a sizeable roid state. A complete blood count before treat- thyroid remnant remains after surgery, ment may be useful. Other laboratory tests and decreased white blood cells that may such as a serum calcium (to exclude hypopar- result in increased susceptibility for in- athyroidism postthyroidectomy) may be help- fection. Generally these