Radioactive iodine uptake scan results

Dear Ask The Doctor: Radioactive iodine uptake test: which has increase iodine uptake, hyperthyroid or hypothyroid?

Dear Adi:A radioactive iodine uptake scan is used to determine whether part or all of the thyroid gland is over or underactive. High radioactive iodine uptake is represented by “hot” nodules, and is secondary to hyperthyroidism. If this is diffuse it may be secondary to Grave’s disease or if a single “hot” nodule is present it may be secondary to a toxic (overactive) nodule. Low radioactive iodine uptake is represented by  “cold” nodules, and is secondary to hypothyroidism. If this is diffuse it may be secondary to thyroiditis (inflammation of the thyroid gland), medications (e.g. amiodarone), or thyroxine replacement. If a single “cold” nodule is present, this requires biopsy to exclude the presence of malignant thyroid disease.