Nuclear thyroid scintigraphy provides both functional and anatomic information in the workup of thyroid disease. Tc-99m-pertechnetate, I-123, or I-131 can be used (iodine is used if measurement of radioactive iodine uptake – RAIU - is desired, useful in most cases). Indications for thyroid scan are as follows:

1. Thyrotoxicosis, including subclinical hyperthyroidism (usually with RAIU) 2. Evaluating functional status of a thyroid nodule (usually with RAIU) 3. Thyroid cancer (typically I-131): RAIU and whole body scan after thyroidectomy, to evaluate for residual disease in neck, lymph nodes, and for distant metastases (also assists in planning RAI therapy) 4. Evaluation of mediastinal masses (i.e. substernal goiter) 5. Detection of ectopic thyroid tissue (i.e. lingual thyroid, esp. in the evaluation of neonatal hypothyroidism)