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Effects of high altitude and cold exposure on resting thyroid hormone concentrations.
Aviat Space Environ Med 1995; 66(4):325-9AS

Abstract

This study examined the effect of high altitude and cold exposure on thyroid hormone status during a mountaineering expedition. There were 15 males participating in an expedition to climb Mt. McKinley, AK. Resting blood samples were collected and analyzed for thyroid-stimulating hormone (TSH), total (T)-free (f) thyroxine (T4), triiodothyronine (T3), reverse T3 (rT3), and cortisol. Measurements were made on three occasions: baseline in the continental U.S. one week pre-expedition (PRE-I), baseline in Alaska immediately pre-expedition (PRE-II), and immediately upon descent post-expedition (POST). Statistical analysis indicated that no significant trial PRE-I vs. PRE-II (p > 0.05) differences occurred. Significant (p < 0.05) reduction, however, occurred from PRE-II to POST expedition in TSH, TT3, and fT3. Also rT3 and cortisol increased significantly PRE-II to POST while TT4 and fT4 were unchanged. The increase (delta = POST minus PRE-II) in cortisol was negatively correlated with the decrease (delta) in TSH (r = -0.52, p = 0.05) and TT3 (r = -0.49, p < 0.06). Moreover, the reduction in TT3 was inversely correlated with the rT3 increase (delta comparison, r = -0.66, p < 0.01). The findings demonstrate that the resting concentrations of thyroid hormones are disrupted by a mountaineering expedition, specifically an environmental stress-related "low T3 condition" seems to develop. These changes would seem to be related to an impaired peripheral conversion of T4 to T3, possibly brought about by elevations in the circulating cortisol levels.

Authors+Show Affiliations

Applied Physiology Laboratory, University of North Carolina, Chapel Hill 27599, USA.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, U.S. Gov't, Non-P.H.S.
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

7794224

Citation

Hackney, A C., et al. "Effects of High Altitude and Cold Exposure On Resting Thyroid Hormone Concentrations." Aviation, Space, and Environmental Medicine, vol. 66, no. 4, 1995, pp. 325-9.
Hackney AC, Feith S, Pozos R, et al. Effects of high altitude and cold exposure on resting thyroid hormone concentrations. Aviat Space Environ Med. 1995;66(4):325-9.
Hackney, A. C., Feith, S., Pozos, R., & Seale, J. (1995). Effects of high altitude and cold exposure on resting thyroid hormone concentrations. Aviation, Space, and Environmental Medicine, 66(4), pp. 325-9.
Hackney AC, et al. Effects of High Altitude and Cold Exposure On Resting Thyroid Hormone Concentrations. Aviat Space Environ Med. 1995;66(4):325-9. PubMed PMID: 7794224.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of high altitude and cold exposure on resting thyroid hormone concentrations. AU - Hackney,A C, AU - Feith,S, AU - Pozos,R, AU - Seale,J, PY - 1995/4/1/pubmed PY - 1995/4/1/medline PY - 1995/4/1/entrez SP - 325 EP - 9 JF - Aviation, space, and environmental medicine JO - Aviat Space Environ Med VL - 66 IS - 4 N2 - This study examined the effect of high altitude and cold exposure on thyroid hormone status during a mountaineering expedition. There were 15 males participating in an expedition to climb Mt. McKinley, AK. Resting blood samples were collected and analyzed for thyroid-stimulating hormone (TSH), total (T)-free (f) thyroxine (T4), triiodothyronine (T3), reverse T3 (rT3), and cortisol. Measurements were made on three occasions: baseline in the continental U.S. one week pre-expedition (PRE-I), baseline in Alaska immediately pre-expedition (PRE-II), and immediately upon descent post-expedition (POST). Statistical analysis indicated that no significant trial PRE-I vs. PRE-II (p > 0.05) differences occurred. Significant (p < 0.05) reduction, however, occurred from PRE-II to POST expedition in TSH, TT3, and fT3. Also rT3 and cortisol increased significantly PRE-II to POST while TT4 and fT4 were unchanged. The increase (delta = POST minus PRE-II) in cortisol was negatively correlated with the decrease (delta) in TSH (r = -0.52, p = 0.05) and TT3 (r = -0.49, p < 0.06). Moreover, the reduction in TT3 was inversely correlated with the rT3 increase (delta comparison, r = -0.66, p < 0.01). The findings demonstrate that the resting concentrations of thyroid hormones are disrupted by a mountaineering expedition, specifically an environmental stress-related "low T3 condition" seems to develop. These changes would seem to be related to an impaired peripheral conversion of T4 to T3, possibly brought about by elevations in the circulating cortisol levels. SN - 0095-6562 UR - https://www.unboundmedicine.com/medline/citation/7794224/Effects_of_high_altitude_and_cold_exposure_on_resting_thyroid_hormone_concentrations_ DB - PRIME DP - Unbound Medicine ER -