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Radioactive Iodine Test

Uptake of tracer doses of radioactive iodine is an essential test in thyroid disease. It is injected into a vein and then binds to receptors on the thyroid cells. This therefore allows the thyroid gland to be imaged on X-ray scanning. There may be a low uptake, a diffuse uniform uptake, a patchy uptake or a solitary hot spot.

A low uptake or no uptake in the thyroid occurs in:

  • Thyroiditis
  • Post partum thyroiditis
  • Iodine-induced thyrotoxicosis
  • Factitious hyperthyroidism (self administered or over replacement of thyroid)

A diffuse uniform uptake in the thyroid occurs in:

Graves' disease.

A patchy uptake in the thyroid occurs in:

Toxic nodular goitre.

A solitary hot spot in the thyroid occurs in:

Plummer's disease

Various different pictures maybe seen with thyroid cancers.