Thyroid scans are functional tests that assess the activity of thyroid gland. Earlier, thyroid scans were done with radioactive iodine. This has largely been replaced by technetium (Tc- 99m) pertechnetate, which involves a much lower radiation dose and costs considerably less.
- Hot nodule: Increased uptake of iodine
- Cold nodule: Decreased uptake of iodine.
- Diffusely increased uptake: Grave’s disease
- Diffusely decreased uptake: Thyroiditis
- Single hot nodule: Solitary toxic nodule
- Multiple hot & cold nodules: Toxic multinodular goiter/ Plummer’s disease.
MCQ [Reference: 27th Bailey]:
- Risk of malignancy in a hot nodule is 4%
- Risk of malignancy in a cold nodule is 20%.
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