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Spaceflight osteopenia refers to the characteristic bone loss that occurs during spaceflight. Astronauts lose an average of more than 1% bone mass per month spent in space.
Risk Of Early Onset Osteoporosis Due To Spaceflight
Osteoporosis results from gradual loss of bone density, so that the skeleton becomes weaker and more susceptible to fractures. Like patients with osteoporosis, astronauts who spend longer periods of time in space also experience bone loss, but at a much faster rate.
They typically experience bone loss in the lower halves of their bodies, particularly in the vertebrae (spine) and the leg bones. The proximal femoral bone (thigh bone) loses 1.5 percent of its mass per month, or roughly 10 percent over a six-month stay in space, with the recovery after returning to
Earth taking at least three or four years.
Currently, the measurement of areal bone mineral density (aBMD) is used at NASA to evaluate the effects of spaceflight on the skeletal health of astronauts.
Notably, there are precipitous declines in aBMD with losses >10 % detected
in the hip and spine in some astronauts following a typical 6-month mission in space. How those percentage changes in aBMD relate to fracture risk in the younger-aged astronaut is unknown.
Risk factors that could be contributing to this bone loss
An astronaut performing exercise in the International Space Station. Credits: JAXA/NASA
Reduced physical activity
ư- Gravity
Radiation
Adaptation to weightlessness
Perturbed mineral metabolism
Suboptimal diet
There is concern that during long duration flights, excessive bone loss and the associated increase in serum calcium ion levels will interfere with execution of mission tasks and result in irreversible skeletal damage.
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After a 3—4 month trip into space, it takes about 2–3 years to regain lost bone density.
Department of Physiological Sciences – Grupo de Investigación en Salud (GIS) No -02INFORMATION CIRCULAR: Spaceflight and osteoporosis.
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1-Jhan Sebastián Saavedra-Torres 2-Luisa Fernanda Zúñiga-Cerón 3-Luisa Fernanda Mahecha Virgüez 4-Alicia Andrea Ortega Narváez 5-María Virginia Pinzón Fernández 6-Nelson Adolfo López Garzón
Credits: NASA
Astronauts take bisphosphonate once a week to prevent bone loss in space. Credits: JAXA/NASA
Recommended Reading: NASA (Laurie J. Abadie, Charles W. Lloyd, Mark J. Shelhamer, NASA Human Research Program) – see link: https://www.nasa.gov/hrp/bodyinspace
Conflicts of interests
None stated by the authors
Financing
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REFERENCES
- Kelly, Scott (2017). Endurance: A Year in Space, A Lifetime of Discovery. With Margaret Lazarus Dean. Alfred A. Knopf, a division of Penguin Random House. p. 174. ISBN 9781524731595.
- Mann, Adam (July 23, 2012). “Blindness, Bone Loss, and Space Farts: Astronaut Medical Oddities”. Wired. Retrieved July 23, 2012.
- Jean D. Sibonga; Evidence Report: Risk of Early Onset Osteoporosis Due to Space Flight- Lyndon B. Johnson Space Center Houston, Texas; Human Health and Countermeasures Element Approved for Public Release: May 9, 2017.
- Williams, D., Kuipers, A., Mukai, C., & Thirsk, R. (2009). Acclimation during space flight: effects on human physiology. Canadian Medical Association Journal, 180(13), 1317-1323.
- Sibonga, J. D., Evans, H. J., Sung, H. G., Spector, E. R., Lang, T. F., Oganov, V. S., … & LeBlanc, A. D. (2007). Recovery of spaceflight-induced bone loss: bone mineral density after long-duration missions as fitted with an exponential function. Bone, 41(6), 973-978.
- “Space Bones”. NASA. October 1, 2001. Retrieved 2012-05-12. 7.Zerwekh JE, Ruml LA, Gotttschalk F, Pak CY (1998) The effects of twelve weeks of bed rest on bone histology, biochemical markers of bone turnover, and calcium homeostasis in eleven normal subjects. J Bone Miner Res 13(10):1594-1601. 8.Sibonga JD; Curr Osteoporos Rep. 2013 Jun;11(2):92-8. doi: 10.1007/s11914-013-0136-5.
Spaceflight-induced bone loss: is there an osteoporosis risk? NASA Johnson Space Center. 9.Zérath E, Grynpas M, Holy X, Viso M, Patterson-Buckendahl P, Marie PJ (2002) Space flight affects bone formation in rhesus monkeys: a histological and cell culture study. J Appl Physiol 93(3):1047- 1056. 10.Zérath E, Novikov V, Leblanc A, Bakulin A, Oganov V, Grynpas M (1996) Effects of space flight on bone mineralization in the rhesus monkey. J Appl Physiol 81(1):194-200.
Consult reports and evidence of human research of NASA “Human Research Roadmap”: • https://humanresearchroadmap.nasa.gov/explore/