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Journal of Thyroid Research
Volume 2012 (2012), Article ID 368536, 4 pages
http://dx.doi.org/10.1155/2012/368536
Research Article

Determinants of Extraocular Muscle Volume in Patients with Graves' Disease

1Specialized Diabetes and Endocrine Centre, King Fahad Medical City, Dabab Street, P.O. Box 59046, Riyadh 11525, Saudi Arabia
2Department of Medicine, Nepean Clinical School, Nepean Hospital, The University of Sydney, Derby Street, P.O. Box 63, Penrith 2751, New South Wales, Australia

Received 26 September 2011; Accepted 30 November 2011

Academic Editor: Leonidas H. Duntas

Copyright © 2012 Samer El-Kaissi and Jack R. Wall. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Background. To examine factors contributing to extraocular muscle (EOM) volume enlargement in patients with Graves’ hyperthyroidism. Methods. EOM volumes were measured with orbital magnetic resonance imaging (MRI) in 39 patients with recently diagnosed Graves’ disease, and compared to EOM volumes of 13 normal volunteers. Thyroid function tests, uptake on thyroid scintigraphy, anti-TSH-receptor antibody positivity and other parameters were then evaluated in patients with EOM enlargement. Results. 31/39 patients had one or more enlarged EOM, of whom only 2 patients had clinical EOM dysfunction. Compared to Graves’ disease patients with normal EOM volumes, those with EOM enlargement had significantly higher mean serum TSH ( 0 . 0 2 0 ± 0 . 0 0 5 versus 0 . 0 0 7 ± 0 . 0 0 2 mIU/L; 𝑃 value 0.012), free-T4 ( 5 2 . 9 ± 3 . 3 versus 4 1 . 2 ± 1 . 7  pmol/L; 𝑃 value 0.003) and technetium uptake on thyroid scintigraphy ( 1 3 . 5 1 ± 1 . 7 % versus 8 . 5 5 ± 1 . 6 % ; 𝑃 value 0.045). There were no differences between the 2 groups in anti-TSH-receptor antibody positivity, the proportion of males, tobacco smokers, or those with active ophthalmopathy. Conclusions. Patients with recently diagnosed Graves’ disease and EOM volume enlargement have higher serum TSH and more severe hyperthyroidism than patients with normal EOM volumes, with no difference in anti-TSH-receptor antibody positivity between the two groups.