July 27, 2016
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Thyroid Scan (cont.)

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When is thyroid scanning helpful?

A thyroid scan can provide information on the size and shape of the gland as well as the overall activity of the gland (is the whole thyroid gland overactive or underactive?).

For example, thyroid scanning is used to determine how active thyroid tissue is in manufacturing thyroid hormone. This feature can determine whether inflammation of the thyroid gland (thyroiditis) is present. It can also detect the presence and degree of overactivity of the gland (hyperthyroidism ). In this case the scan reveals increased iodine uptake by the whole gland.

In addition, a thyroid scan can provide information on specific areas within the thyroid gland and can help to determine whether any localized areas are hyperfunctioning or under functioning compared to the rest of the gland. In these cases spots appear on the image corresponding to areas that take up iodine differently from the rest of the gland.

Thyroid scanning is especially helpful in evaluating thyroid nodules, particularly after a fine needle aspiration biopsy has failed to provide a diagnosis. A scan will reveal whether a thyroid nodule is "functioning" or "nonfunctioning". Doctors refer to hyper functioning nodules of the thyroid (those that are actively taking up iodine to produce thyroid hormone more so than surrounding thyroid tissue) as "hot" nodules, and these hyperfunctioning areas are seen on the image of the thyroid gland. A nonfunctioning nodule does not take up iodine and produces a localized "cold" area on the image of the thyroid gland.

In addition, thyroid scanning can be done to help determine if thyroid cancer has spread beyond the bed of the thyroid in the neck. For this purpose, usually a whole body thyroid scan is performed.

Medically Reviewed by a Doctor on 6/11/2015

Source: MedicineNet.com

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