Increased need for thyroid hormone leads to a signal pathway mediated by thyroid stimulating hormone (TSH) leading to release of active hormone from a bound state with thyroglobulin to a free state, eventually being secreted into the blood stream. When there is hypersecretion of thyroid hormones due to any cause, the condition is known as hyperthyroidism. Usually hyperthyroidism is indicated by an elevated level of TSH. Therefore, in clinical practice the diagnosis of hyperthyroidism is made by finding an abnormally elevated TSH level which would indicate measurements of circulating thyroid hormone levels, ultimately confirming the diagnosis of hyperthyroidism (Flower et al. There are several interpretations of bound and unbound thyroid hormones to point to the accurate aetiological diagnosis of hyperthyroidism. However, this is not the case always. There are many physiological conditions which demonstrate higher total thyroid hormone levels due to the fact that those conditions lead to an elevated thyroid binding globulin. Likewise, there are several clinical conditions where the TSH level estimation as a screening test fails to point to the exact diagnosis of hyperthyroidism. This is more so when unbound T4 estimations are not parts of the investigative protocol (Intenzo et al. Many extrathyroid diseases may lead to an abnormal TSH level. Similar artifacts in interpretation in laboratory data may appear in certain other conditions. For example, decreased TSH, the hallmark of hyperthyroidism may be noted physiologically in the first trimester of pregnancy, following treatment of hyperthyroidism, even as a result of some medications, and more significantly in cases of hypothalamic-pituitary diseases. Certain other clinical tests are also not useful in such cases. A particular property of thyroid gland can be used to diagnose such cases. The thyroid gland is known to selectively transport radioisotopes of iodine, 123I, 125I, and 131I and 99mTC pertechnetate. This can be used to allow thyroid imaging through quantification of fractional uptake of these radioactive tracers (Wu and Weiss, 2006). This highlights one of the uses of nuclear medicine in imaging modalities used in hyperthyroidism. There are many other modalities of imaging available aside from the nuclear medicine imaging techniques, and in this assignment the relevant literature will be evaluated to update knowledge in this area, so this can be clinically useful.Appropriate recent
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What is hyperthyroidism?
What different imaging modalities may be used in diagnosing hyperthyroidism?
Can imaging modalities differentiate between aetiologies of hyperthyroidism?
In relation to hyperthyroidism, what best can be diagnosed by radionuclide imaging?
Can radionuclide scintigraphy be used in combination with other imaging modalities?
What are the roles of PET and MRI scanning in relation to hyperthyroidism?
What radionuclides are used for scintigraphy of the thyroid gland?
What are the hormones that are released from the thyroid gland?
Provide an example where ultrasonography may be better that nuclear imaging?
What would be guidelines for using nuclear imaging in diagnosis of hyperthyroidism?
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