| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
Department of Environmental Medicine, Naval Medical Research Institute (H.L.R.) Bethesda, Maryland 20814-5055
the Departments of Nuclear Medicine (E.D.S.) and Medicine (H.L.R., K.M.M.S., R.D., K.D.B., J.T.O.) and the Endocrine-Metabolic Service (H.L.R., K.M.M.S., R.D., J.T.O.), National Naval Medical Center, and the Departments of Medicine (H.L.R., KM.M.S., R.D., J.T.O.) and Radiology and Nuclear Medicine (E.D.S.), Uniformed Services University of the Health Sciences Bethesda, Maryland 20814-5011
the Department of Medicine, Endocrine and Metabolic Service, Kyle Metabolic Unit, Department of Clinical Investigation, Walter Reed Army Medical Center (K.D.B.) Washington, D.C. 20307-5100
Address all correspondence and requests for reprints to: H. L. Reed, M.D., Mail Stop 11, Environmental Medicine Department, Naval Medical Research Institute, Bethesda, Maryland 20814-5055.
Humans who live in Antarctica for greater than 5 continuous months demonstrate alterations in the hypothalamic-pituitary-thyroid axis. These changes are characterized by 1) increased pituitary release of TSH in response to iv TRH, 2) increased serum clearance of orally administered T3, and 3) normal serum total, free T4, and unstimulated TSH levels. To clarify the mechanism responsible for these findings, serum kinetic studies of 125I-labeled T4 and T3 were carried out in a group of normal men, first in California, then after 20 and 42 weeks of continuous Antarctic residence. The kinetic parameters were calculated by noncompartmental analysis. The mean T4 residence time (MRT) was not different before and after 42 weeks (5.54 ± 0.50 and 5.08 ± 0.43 days). The total T4 volume of distribution (TVd) tended to fall over the same period (4.30 ± 0.12, 3.56 ± 0.27 L/m2), but was not significantly different (P = 0.075). In contrast to T4, there was an increase from control values for the T3 MRT from 0.83 ± 0.03 to 1.10 ± 0.03 days (P < 0.002) and a more than doubling of the T3 TVd from 15.55 ± 0.52 to 47.24 ± 5.09 L/m2 (P < 0.002) after 42 wk of Antarctic residence. Energy intake increased approximately 40% throughout the study without a change in body weight. The changes in T3 kinetic parameters may be accounted for by increased extravascular tissue binding. The marked increase in T3 TVd and the small increase in MRT are associated with increased T3 production and clearance and only minor changes in T4 kinetics. This is the first description of a mechanism for the change in thyroid hormone economy occurring with extended residence in Antarctica.
* The opinions expressed herein are those of the authors and are not to be construed as reflecting the views of the Department of the Navy, the Department of the Army, the Department of Defense, or the NSF. This work was supported in part by U.S. Navy Research and Development Command work unit 63706N M0095.004.1008 and NSF Grant S-035.
Received April 14, 1989.
This article has been cited by other articles:
![]() |
A. G. Burger Environment and Thyroid Function J. Clin. Endocrinol. Metab., April 1, 2004; 89(4): 1526 - 1528. [Full Text] [PDF] |
||||
![]() |
N. Van Do, L. Mino, G. R. Merriam, H. LeMar, H. S. Case, L. A. Palinkas, K. Reedy, and H. L. Reed Elevation in Serum Thyroglobulin during Prolonged Antarctic Residence: Effect of Thyroxine Supplement in the Polar 3,5,3'-Triiodothyronine Syndrome J. Clin. Endocrinol. Metab., April 1, 2004; 89(4): 1529 - 1533. [Abstract] [Full Text] [PDF] |
||||
![]() |
J. Leppaluoto, I. Korhonen, and J. Hassi Habituation of thermal sensations, skin temperatures, and norepinephrine in men exposed to cold air J Appl Physiol, April 1, 2001; 90(4): 1211 - 1218. [Abstract] [Full Text] [PDF] |
||||
![]() |
H. L. Reed, K. R. Reedy, L. A. Palinkas, N. Van Do, N. S. Finney, H. S. Case, H. J. LeMar, J. Wright, and J. Thomas Impairment in Cognitive and Exercise Performance during Prolonged Antarctic Residence: Effect of Thyroxine Supplementation in the Polar Triiodothyronine Syndrome J. Clin. Endocrinol. Metab., January 1, 2001; 86(1): 110 - 116. [Abstract] [Full Text] |
||||
![]() |
D. J. Lugg Antarctic Medicine JAMA, April 26, 2000; 283(16): 2082 - 2084. [Full Text] [PDF] |
||||
![]() |
L. A. Palinkas Effects of Physical and Social Environments on the Health and Well-Being of Antarctic Winter-Over Personnel Environment and Behavior, November 1, 1991; 23(6): 782 - 799. [Abstract] |
||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Endocrinology | Endocrine Reviews | J. Clin. End. & Metab. |
| Molecular Endocrinology | Recent Prog. Horm. Res. | All Endocrine Journals |