Diagnostic Imaging Pathways - Hyperthyroidism
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This pathway provides guidance on the investigation of adult patients with hyperthyroidism.
Date reviewed: January 2012
Date of next review: January 2015
Published: January 2012
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|SYMBOL||RRL||EFFECTIVE DOSE RANGE|
|Minimal||< 1 millisieverts|
- Graves' disease can often be diagnosed clinically and appropriate medication commenced
- If the aetiology of hyperthyroidism is uncertain, scintigraphy may aid in the diagnosis based on the pattern and location of radionuclide uptake
- Hyperthyroidism is diagnosed when there is elevation of serum free T3 and/or T4 accompanied by typical symptoms and signs. Biochemical evidence without clinical manifestations is referred to as subclinical hyperthyroidism
- Common causes of hyperthyroidism include Graves' disease, toxic multinodular goitre, functioning thyroid adenoma and thyroiditis
- The role of imaging in hyperthyroidism is to help establish the cause and this is usually done with a thyroid scintigraphy scan
- Elevated T3 and T4 is usually accompanied by low levels of TSH. However, rarely hyperthyroidism is driven by high TSH levels in which case a TSH-secreting pituitary adenoma should be excluded
- Typical cases of Graves' disease such as those with a diffuse goitre, ophthalmopathy and serological evidence may treated without any prior imaging although scintigraphy may help confirm the diagnosis and exclude other causes
- Usually performed with technetium-99m pertechnetate or radioiodine ,,
- Advantages of technetium-99m pertechnetate ,,
- Lower radiation dose
- Better image quality
- Less waiting time after administration
- Wider availability
- Lower cost
- Images can be obtained while the patient is taking anti-thyroid medications.
- Advantages of radioiodine ,,,
- Has lower levels of vascular background activity which is useful when assessing retrosternal masses
- Has some advantages in the evaluation of thyroid nodules, although these are rarely of clinical significance
- Oral administration
- Scintigraphy is particularly useful for distinguishing Graves' disease from conditions such as subacute, silent and postpartum thyroiditis and factitious hyperthyroidism ,
- It is also useful for demonstrating toxic adenomas
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- Meller J, Becker W. The continuing importance of thyroid scintigraphy in the era of high-resolution ultrasound. Eur J Nucl Med Mol Imaging. 2002;29:425-38. (Review article)
- Kusic Z, Becker DV, Saenger EL, et al. Comparison of technetium-99m and iodine-123 imaging of thyroid nodules: Correlation with pathologic findings. J Nucl Med. 1990;31:393-9. (Level III evidence)
- Intenzo CM, dePapp AE, Jabbour S, et al. Scintographic manifestations of thyrotoxicosis. Radiographics. 2003;23:857-69. (Review article)
- Price DC. Radioisotopic evaluation of the thyroid and the parathyroids. Radiol Clin North Am. 1993;31:991-1015. (Review article)
- Meier DA, Kaplan MM. Radioiodine uptake and thyroid scintigraphy. Endocrinol Metab Clin North Am. 2001;30:291-313. (Review article)
- Summaria V, Salvatori M, Rufini V, et al. Diagnostic imaging in thyrotoxicosis. Rays. 1999;24:273-300. (Review article)
- Naik KS, Bury RF. Review: Imaging the thyroid. Clin Radiol. 1998;53:630-9. (Review article)
- Smith JR, Oates E. Radionuclide imaging of the thyroid gland: patterns, pearls, and pitfalls. Clin Nucl Med. 2004;29:181-93. (Review article)
- Ross DS. Diagnosis of hyperthyroidism. In: UpToDate, Basow, DS(Ed), UpToDate, Waltham, MA, 2009. (Review article)
- Ross DS. Disorders that cause hyperthyroidism. In: UpToDate, Basow, DS(Ed), UpToDate, Waltham, MA, 2009. (Review article)
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