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Radioactive Iodine Uptake Scan

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Radioactive Iodine Uptake Scan, Radioiodine Uptake, Thyroid Iodine Uptake, RAIU, Radioiodine Thyroid Imaging Study

  • Indications
  1. Hyperthyroidism diagnosis and management
  • Mechanism
  1. Iodine-123 (I-123) uptake by the Thyroid Gland is measured
  2. Typical uptake is 15-25% in 24 hours
  • Causes
  • Diffusely Low radioidoine uptake with hyperthyrodism
  1. Medications and other intakes
    1. Exogenous Thyroid intake
    2. Excessive exogenous Iodine
    3. Amiodarone
  2. Transient Thyroiditis
    1. Subacute Thyroiditis
    2. Postpartum Thyroiditis (5-8% Incidence)
    3. Painless lymphocytic Thyroiditis
  1. Requires biopsy for Thyroid Cancer evaluation
  1. Diffusely increased uptake
    1. Thyrotoxicosis (e.g. Grave's Disease)
  2. Localized increased uptake (Hot Nodule)
    1. Hyperfuntioning Thyroid Nodule