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Eur J Appl Physiol (2008) 103:285288 DOI 10.1007/s00421-008-0701-2
ORIGINAL ARTICLE
EVect of hyperthermia on the function of thyroid gland
S. Mustafa M. D. Al-Bader A. H. Elgazzar J. Alshammeri S. Gopinath H. Essam
Accepted: 14 February 2008 / Published online: 5 March 2008 Springer-Verlag 2008
Abstract Hyperthermia may be a consequence of environmental conditions, bacterial or viral infections and/or thyroid storm. This study investigates the acute eVect of body temperature elevation on thyroid function and on its scintigraphy studies. Thyroid scintigraphy was performed on New Zealand White rabbits weighing approximately 33.5 kg. Each rabbit was injected with 115 MBq (3.1 mCi) technetium-99 m pertechnetate (99mTc pertechnetate). Studies were performed using Gamma camera equipped with a low energy, high resolution, pinhole collimator interfaced with a computer. Static images were acquired 20 min after administration of the radiotracer. Two days later the same protocol was repeated for the same rabbit after increasing the body temperature by 2C. The experiment was repeated again after a 2-day interval at 3C, and then after another 2-day interval at 4C. Plasma free thyroxine (FT4), free triiodothyronine (FT3) and thyroid stimulating hormone (TSH)
were measured at control and at diVerent hyperthermic temperatures (+2, 3, 4C). We recorded isometric tension of rabbit thyroid artery strips in organ baths during stepwise temperature elevation. During hyperthermia the decrease in thyroid function and thyroid scintigraphy studies was
proportional to body temperature elevation. The recording of isometric tension in rabbit thyroid artery strips in organ baths showed vasoconstriction during hyperthermia which is proportional to the heating temperature. Plasma FT4 and
FT3 level were decreased while TSH levels were not aVected by acute fever. Our results indicate that hyperthermia causes a transient decrease in thyroid gland function and scintigraphic patterns on radionuclide studies. Thus, body temperatures must be measured before radionuclide studies in order to ensure that interpretation of data is not inXuenced by hyperthermia.
Keywords Fever Thyroxine Carotid artery Thyroid artery Rabbit
Introduction
The thyroid follicle consists of epithelial cells surrounding a colloid center which acts as a storage site for thyroid hormones. The thyroid epithelial cell has a transport mechanism that enables thyroid concentration of iodide far in excess of that in the plasma (WolV 1964; De la Vieja et al. 2000). A plasma membrane protein,...