What's the purpose of thyroid scan?

A thyroid scan: Uses a radioactive tracer and a special camera to measure how much tracer the thyroid gland absorbs from the blood. A thyroid scan can show the size, shape, and location of the thyroid gland. It also finds areas that are overactive or underactive and to evaluate possible masses that may be felt or seen with ultrasound.

Thyroid function: Thyroid uptake and scan is a functional imaging study use to evaluate the functional status of your thyroid gland based on iodine uptake and distribution. It gives a useful clinical index of thyroid function (hyper or hypo ) and is mainly used to differentiate graves disease from sub-acute thyroiditis, factitious hyperthyroidism and toxic nodular goiter among other indications.

Dx thyroid disease: A "thyroid scan" may refer to an ultrasound, which can document size and nodules. Helps with needle biopsy. Also may refer to a nuclear scan, which images thyroid function and to a lesser extent (compared to ultrasound) thyroid size. Scans are used primarily to evaluate nodules or hyperthyroidism. Scans not always used in elderly pts with hypothyroidism.