Iodide ion I-123 is the most suitable isotope of iodine for the diagnostic study of thyroid diseases. Sodium Iodide I 131 Capsules Diagnostic is indicated for use in adults for: Assessment of thyroid function using radioactive iodine (RAI) uptake test and Imaging the thyroid (scintigraphy). The following adverse reaction has been described elsewhere in the labeling: Hypersensitivity Reactions. The following adverse reactions have been identified during post-approval use from Sodium Iodide I 131 Capsules Diagnostic: Gastrointestinal disorders (vomiting, nausea, and diarrhea); General disorders and administration site conditions (local thyroid swelling); Immune system disorders (hypersensitivity reactions); Skin and subcutaneous tissue disorders (itching, rash, hives, and erythema). Certain drugs and iodine-containing foods interfere with the accumulation of radioiodide by the thyroid.

Molybdenum-99 (99Mo, half-life = 66 h) is a parent radionuclide of a diagnostic nuclear isotope. It decays in technetium-99 m (half-life = 6 h), which is used in over 30 million procedures per year around the world. Between 95 and 98 percent of Mo-99 is currently being produced using highly enriched uranium (HEU) targets. Other medical isotopes such as iodine-131 (I-131) and xenon-133 (Xe-133) are by-products of the Mo-99 production process and will be sufficiently available if Mo-99 is available.

Iodide I-131 (as Sodium iodide I-131) is a radioisotopic drug used for the treatment and palliation of thyroid malignancy. Therapeutic solutions of Sodium Iodide-131 are indicated for the treatment of hyperthyroidism and thyroid carcinomas that take up iodine. Palliative effects may be observed in patients with advanced thyroid malignancy if the metastatic lesions take up iodine. It is also indicated for use in performance of the radioactive iodide (RAI) uptake test to evaluate thyroid function. Taken orally, sodium iodide I-131 is rapidly absorbed and distributed within the extracellular fluid of the body. The iodide is concentrated in the thyroid via the sodium/iodide symporter, and subsequently oxidized to iodine. The destruction of thyroidal tissue is achieved by the beta emission of sodium iodide I-131.

Iodine-124 (124I), a positron emission tomography (PET) radiotracer, can be used in a variety of PET applications, such as protein and antibody iodinations, as well as in the design and synthesis of new PET tracers. I-124 has the potential to improve the current clinical practice in the diagnosis and treatment of differentiated thyroid cancer (DTC). In addition, 124 PET/CT is a sensitive tool to detect some new lesions that are not visualized on the post-treatment I-131 scan. Recently published article has described that in order to I-124 used as a mainstream, this substance should be more commercially available and at a more chipper.