II. Indications
- Hyperthyroidism diagnosis and management
III. Mechanism
- Iodine-123 (I-123) uptake by the Thyroid Gland is measured
- Typical uptake is 15-25% in 24 hours
IV. Causes: Diffusely Low radioidoine uptake with hyperthyrodism
- Medications and other intakes
- Exogenous Thyroid intake
- Excessive exogenous Iodine
- Amiodarone
- Transient Thyroiditis
- Subacute Thyroiditis
- Postpartum Thyroiditis (5-8% Incidence)
- Painless lymphocytic Thyroiditis
V. Causes: Focal low RAIU (cold Nodule) with Hypothyroidism
- Requires biopsy for Thyroid Cancer evaluation
VI. Causes: High Radioiodine Uptake with Hyperthyroidism
- Diffusely increased uptake
- Thyrotoxicosis (e.g. Grave's Disease)
- Localized increased uptake (Hot Nodule)
- Hyperfuntioning Thyroid Nodule