Sodium Iodide-I-131 Dosage

Usual Adult Dose for:

Hyperthyroidism
Thyroid Cancer
Diagnostic

Additional dosage information:

Renal Dose Adjustments
Liver Dose Adjustments
Precautions
Dialysis
Other Comments

Usual Adult Dose for Hyperthyroidism

Simplest method to determine dose: Administer the same amount of sodium iodide-I-131, nominally 148 to 370 megabecquerels (4 to 10 millicuries), to all patients having similar clinical condition of hyperthyroidism.

Most common method for determining amount of sodium iodide-I-131 to give to a hyperthyroid patient is based on the estimate of the 24 hour thyroid uptake and the mass of the gland (mass of gland is determined by palpitation or thyroid imaging. Administered dose = microcurie per gram x mass of thyroid (g) x 100 divided by the 24 hour thyroid uptake (%). Most clinicians use a dosage of 55 to 80 microcuries per gram for Graves' disease. For very enlarged glands and severely hyperthyroid patients, larger doses of 160 to 200 microcuries per gram are given.

Usual Adult Dose for Thyroid Cancer

Initial dose (ablation): 925 to 1110 megabecquerels (25 to 30 millicuries), although doses as high as 5550 megabecquerels (150 millicuries) have been used.

Therapeutic dose: 3700 to 7400 megabecquerels (100 to 200 millicuries) depending on the extent of metastatic sites. Smaller doses are given for cancer remnants in the thyroid bed or cervical lymph nodes and larger doses are given for lung and bone metastases.

Usual Adult Dose for Diagnostic

Thyroid uptake: 0.185 to 0.555 megabecquerels (5 to 15 microcuries). Thyroid uptake values should be determined at 6 hours and 24 hours after administration.

Scinitiscanning: 1.85 to 3.7 megabecquerels (50 to 100 microcuries).

Localization of extra-thyroidal metastases: 37 megabecquerels (1000 microcuries).

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Precautions

Sodium iodide-I-131 is not usually used for treatment of hyperthyroidism in patients under 30 years of age.

Care should be taken to minimize radiation exposure to the patient and occupational workers.

The uptake of radioiodide will be affected by recent intake of stable iodine in any form, or by use of thyroid, antithyroid, and certain other drugs. The patients should be questioned carefully regarding previous medication and procedures involving radiographic contrast media.

Radioiodide therapy in women of childbearing age should only be performed when appropriate contraceptive measures have been taken or when pregnancy testing is negative.

Radiopharmaceuticals should be used only by physicians who are qualified by training and experience in the safe handling of radionuclides.

Patients should be adequately hydrated before and after administration of sodium iodide-I-131 to assure rapid urinary elimination of the iodide that is not absorbed by the thyroid.

Dialysis

Data not available

Other Comments

The patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration.

Waterproof gloves should be used during the entire handling and administration procedure. Adequate shielding should be maintained during the life of the product.