Abstract:
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Purpose: Defined as suppressed thyroid stimulating hormone (TSH) levels with normal serum thyroid hormone (T3 and T4) levels, subclinical hyperthyroidism (SBH) has come to clinical attention with increasing frequency over the past few years. Our aim is to categorize the thyroid scan findings of SBH according to etiology of the underlying thyroid disorder, and to determine the frequency with which SBH evolves into overt hyperthyroidism with each disorder.
Methods and Materials: Over the past 5 years, a total of 73 patients with SBH underwent thyroid scintigraphy. Whenever possible, follow-up was obtained by either contacting the referring physician or by review of medical records. The results of any follow-up thyroid scans were recorded.
Results: 41 of the 73 patients evaluated (56.16%) had an autonomously functioning thyroid nodule (AFTN), 22 patients (30.14%) had a multinodular goiter (MNG), 7 patients (9.59%) demonstrated a diffuse enlarged gland with uniformly increased activity and were termed "evolving Graves disease"(EGD). The remaining 3 patients (4.10%) were assumed to have resolving silent thyroiditis (RST). 10 of the 41 patients with AFTN were lost to follow-up; of the remaining 31 patients with AFTN, 22 progressed to overt hyperthyroidism (i.e. toxic adenoma), while 9 remained stable. 6 of the 22 patients with MNG were lost to follow-up; of the remaining 16, 7 progressed to a toxic MNG, while 9 remained stable. One of the 7 patients with EGD was lost to follow-up, while the remaining 6 progressed to Graves' disease. All 3 of the patients with RST became enthyroid spontaneously.
Conclusion: 1. More than half of the patients with SBH in this series had an AFTN, and most progressed to a toxic adenoma. 2. All of the patients followed with evolving Graves' disease became thyrotoxic. 3. Less than half of the patients with MNG who were followed became thyrotoxic (i.e. toxic MNG).
Questions about this event email: charles.intenzo@mail.tju.edu
Intenzo MD, C,
Scintigraphic Manifestations of Subclinical Hyperthyroidism: A 5-Year Analysis. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3102776.html
