Population Covered By The Guidance
This pathway provides guidance on the investigation of adult patients with hyperthyroidism.
Date reviewed: February 2018
Date of next review: June 2023
Published: June 2018
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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, isotope scan may aid in the diagnosis based on the pattern and location of radionuclide uptake
- Hyperthyroidism is diagnosed when there is elevation of serum free T4 and/or T3 accompanied by typical symptoms and signs. Biochemical evidence without clinical manifestations is referred to as subclinical hyperthyroidism. Antibody interference in thyroid assays should be considered when interpreting results
- Common causes of hyperthyroidism include Graves' disease and toxic multinodular goitre; also consider 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 isotope scan
- Elevated T3 and T4 are usually accompanied by low levels of TSH. However, rarely hyperthyroidism is driven by high TSH levels in which case a TSH-secreting pituitary adenoma or thyroid hormone resistance 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
Thyroid Isotope Scan (Thyroid Scintigraphy)
- 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
Date of literature search: September 2017
References are graded from Level I to V according to the Oxford Centre for Evidence-Based Medicine, Levels of Evidence. Download the document
- De Leo S, Lee SY, Braverman LE. Hyperthyroidism. Lancet. 2016;388(10047):906-18. (Review article). View the reference
- Lacka K, Fraczek MM. Classification and etiology of hyperthyroidism. Polski merkuriusz lekarski : organ Polskiego Towarzystwa Lekarskiego. 2014;36(213):206-11. (review article). View the reference
- 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 Suppl 2:S425-38. (Review article). View the reference
- Summaria V, Salvatori M, Rufini V, Mirk P, Garganese MC, Romani M. Diagnostic imaging in thyrotoxicosis. Rays. 1999;24(2):273-300. (Review article). View the reference
- Alimanovic-Alagic R, Brkovic A, Kucukalic-Selimovic E, Skopljak-Beganovic A. Thyroid scintigraphy as diagnostic method evaluation of thyroid diseases. Med Arh. 2008;62(2):114-6. (Review article). View the reference
- Smith JR, Oates E. Radionuclide imaging of the thyroid gland: patterns, pearls, and pitfalls. Clin Nucl Med. 2004;29(3):181-93. (Review article). View the reference
- Intenzo CM, dePapp AE, Jabbour S, Miller JL, Kim SM, Capuzzi DM. Scintigraphic manifestations of thyrotoxicosis. Radiographics. 2003;23(4):857-69. (Review article). View the reference
- Kusic Z, Becker DV, Saenger EL, Paras P, Gartside P, Wessler T, et al. Comparison of technetium-99m and iodine-123 imaging of thyroid nodules: correlation with pathologic findings. J Nucl Med. 1990;31(4):393-9. (Level III evidence). View the reference
- Gupta V. Physiopathologic atlas of thyroid scintigraphy. Kathmandu University medical journal (KUMJ). 2007;5(4):583-90. (Review article). View the reference
- Meng Z, Zhang G, Sun H, Tan J, Yu C, Tian W, et al. Differentiation between Graves' disease and painless thyroiditis by diffusion-weighted imaging, thyroid iodine uptake, thyroid scintigraphy and serum parameters. Experimental and Therapeutic Medicine. 2015;9(6):2165-72. (Level III evidence). View the reference
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