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Clinical Trial
. 2012 Jan;97(1):270-8.
doi: 10.1210/jc.2011-2233. Epub 2011 Nov 2.

Long-duration space flight and bed rest effects on testosterone and other steroids

Scott M Smith  1 , Martina Heer, Zuwei Wang, Carolyn L Huntoon, Sara R Zwart
Affiliations
Clinical Trial

Long-duration space flight and bed rest effects on testosterone and other steroids

Scott M Smith et al. J Clin Endocrinol Metab. 2012 Jan.

Erratum in

  • J Clin Endocrinol Metab. 2012 Sep;97(9):3390

Abstract

Context: Limited data suggest that testosterone is decreased during space flight, which could contribute to bone and muscle loss.

Objective: The main objective was to assess testosterone and hormone status in long- and short-duration space flight and bed rest environments and to determine relationships with other physiological systems, including bone and muscle.

Design: Blood and urine samples were collected before, during, and after long-duration space flight. Samples were also collected before and after 12- to 14-d missions and from participants in 30- to 90-d bed rest studies.

Setting: Space flight studies were conducted on the International Space Station and before and after Space Shuttle missions. Bed rest studies were conducted in a clinical research center setting. Data from Skylab missions are also presented.

Participants: All of the participants were male, and they included 15 long-duration and nine short-duration mission crew members and 30 bed rest subjects.

Main outcome measures: Serum total, free, and bioavailable testosterone were measured along with serum and urinary cortisol, serum dehydroepiandrosterone, dehydroepiandrosterone sulfate, and SHBG.

Results: Total, free, and bioavailable testosterone was not changed during long-duration space flight but were decreased (P < 0.01) on landing day after these flights and after short-duration space flight. There were no changes in other hormones measured. Testosterone concentrations dropped before and soon after bed rest, but bed rest itself had no effect on testosterone.

Conclusions: There was no evidence for decrements in testosterone during long-duration space flight or bed rest.

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Figures

Fig. 1.
Fig. 1.
Urinary testosterone in Skylab crew members before and during flight on Skylab missions 2, 3, and 4 in 1973–1974 (n = 9 for all time points except FD31–40 and FD41–50, where n = 6). Data are mean ± sd and are adapted from elsewhere (34). Urinary testosterone excretion on FD11–20 was higher than on FD1–10 (P < 0.05) but not different from other time points.
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References

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