Sodium Iodide I-131 is not usually used for the treatment of hyperthyroidism in patients under 30 years of age unless circumstances preclude other methods of treatment.
The recent intake of stable iodine in any form, or the use of thyroid or anti-thyroid drugs will affect the uptake of radioiodide. Accordingly, the patient should be questioned carefully regarding previous medication and procedures involving radiographic contrast media.
- Hyperthyroidism and thyrotoxic cardiac disease may be aggravated by radiation thyroiditis. Pre-treatment and posttreatment with antithyroid agents and/or beta-blockers, such as propranolol should be considered.
- Low serum chlorides or nephrosis may increase thyroid uptake of Sodium Iodide I-131.
- Renal function impairment may decrease excretion of radio-iodide and increase the amount of radiation exposure.
Radiopharmaceuticals should be used only by nuclear physicians and/or radiopharmacists who are qualified by training and experience in the safe use and handling of radionuclides, and whose experience and training have been approved by the appropriate governmental agency authorized to license the use of radionuclides (See Drug Handling And Final Dosage Form Preparation section).
As in the use of any radioactive material, care should be taken to minimize radiation exposure to the patient consistent with proper patient management and to assure minimum radiation exposure to occupational workers.
Experiments in animals with Sodium Iodide I-131 have demonstrated that radioiodide administration can induce thyroid adenomas and carcinomas. However, studies in humans have shown no conclusive evidence of thyroid carcinoma in hyperthyroid patients treated with Sodium Iodide I-131.
Mutagenic effects have not been clearly established in clinical studies of patients treated with Sodium Iodide I-131. However, chromosomal changes have been reported in laboratory studies.
Impairment of Fertility
A follow-up study of 627 women treated for differentiated thyroid carcinoma with Sodium Iodide I-131 revealed no evidence of fertility impairment.
Pregnancy Category X
See CONTRAINDICATIONS section.
Sodium Iodide I-131 may cause fetal harm to the thyroid gland when administered to a pregnant woman.
The possibility of pregnancy should be assessed in women of childbearing potential. To avoid the possibility of fetal exposure to radiation, in those circumstances where the patient's pregnancy status is uncertain, a pregnancy test should be performed. Radioiodide therapy for the treatment of thyroid disease in women of childbearing age should only be performed when appropriate contraceptive measures have been taken or when pregnancy testing is negative.
Adequate and well controlled studies have not been performed in animals.
Sodium Iodide I-131 is distributed into breast milk and may reach concentrations equal to or greater than concentrations in maternal plasma. Formula feeding should be substituted for breast feeding until radiation levels have substantially decreased.
Safety and efficacy in pediatric patients have not been established. (See WARNINGS section).
Adequate and well controlled studies on the relationship of age to the effect of radioiodide have not been performed in geriatric population.
This drug is known to be substantially excreted by the kidney and the risk of toxic reactions to this drug may be greater in patients with impaired renal function. Because elderly patients are more likely to have decreased renal function, care should be taken in dose selection and it may be useful to monitor renal function.
Last reviewed on RxList: 10/6/2011
This monograph has been modified to include the generic and brand name in many instances.
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