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Renal Stone Risk During Space Flight: Assessment and Countermeasure ValidationNASA has focused its future on exploration class missions including the goal of returning to the moon and landing on Mars. With these objectives, humans will experience an extended exposure to the harsh environment of microgravity and the associated negative effects on all the physiological systems of the body. Exposure to microgravity affects human physiology and results in changes to the urinary chemical composition during and after space flight. These changes are associated with an increased risk of renal stone formation. The development of a renal stone would have health consequences for the crewmember and negatively impact the success of the mission. As of January 2007, 15 known symptomatic medical events consistent with urinary calculi have been experienced by 13 U.S. astronauts and Russian cosmonauts. Previous results from both MIR and Shuttle missions have demonstrated an increased risk for renal stone formation. These data have shown decreased urine volume, urinary pH and citrate levels and increased urinary calcium. Citrate, an important urinary inhibitor of calcium-containing renal stones binds with calcium in the urine, thereby reducing the amount of calcium available to form calcium oxalate stones. Urinary citrate also prevents calcium oxalate crystals from aggregating into larger crystals and into renal stones. In addition, citrate makes the urine less acidic which inhibits the development of uric acid stones. Potassium citrate supplementation has been successfully used to treat patients who have formed renal stones. The evaluation of potassium citrate as a countermeasure has been performed during the ISS Expeditions 3-6, 8, 11-13 and is currently in progress during the ISS Expedition 14 mission. Together with the assessment of stone risk and the evaluation of a countermeasure, this investigation provides an educational opportunity to all crewmembers. Individual urinary biochemical profiles are generated and the risk of stone formation is estimated. Increasing fluid intake is recommended to all crewmembers. These results can be used to lower the risk for stone formation through lifestyle, diet changes or therapeutic administration to minimize the risk for stone development. With human presence in microgravity a continuing presence and exploration class missions being planned, maintaining the health and welfare of all crewmembers is critical to the exploration of space.
Document ID
20070008213
Acquisition Source
Johnson Space Center
Document Type
Conference Paper
Authors
Whitson, P. A. (NASA Johnson Space Center Houston, TX, United States)
Sams, C. F. (NASA Johnson Space Center Houston, TX, United States)
Jones, J. A. (NASA Johnson Space Center Houston, TX, United States)
Pietrzke, R. A. (Wyle Labs., Inc. Houston, TX, United States)
Nelman-Gonzalez, M. A. (Wyle Labs., Inc. Houston, TX, United States)
Hudson, E. K. (JES Tech Houston, TX, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2007
Subject Category
Aerospace Medicine
Meeting Information
Meeting: NASA Human Research Program Investigators'' Meeting
Location: League City, TX
Country: United States
Start Date: February 12, 2007
End Date: February 14, 2007
Distribution Limits
Public
Copyright
Public Use Permitted.

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