RENAL STONE RISK ASSESSMENT DURING SPACE SHUTTLE FLIGHTS |
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Authors: | Peggy A Whitson Robert A Pietrzyk Charles YC Pak |
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Institution: | aFrom the Medical Sciences Division, NASA/Johnson Space Center, KRUG Life Sciences Inc., Houston, and the Section of Mineral Metabolism, Southwestern Medical School, University of Texas Health Science Center, Dallas, Texas. bAccepted for publication July 15, 1997. c(Whitson) Requests for reprints: Astronaut Office, Mail Code CB, NASA/Johnson Space Center, Houston, TX 77058. dFunded as part of the Johnson Space Center Extended Duration Orbiter Medical Project. |
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Abstract: | PurposeThe metabolic and environmental factors influencing renal stone formation before, during, and after Space Shuttle flights were assessed. We established the contributing roles of dietary factors in relationship to the urinary risk factors associated with renal stone formation.Materials and Methods24-hr. urine samples were collected prior to, during space flight, and following landing. Urinary and dietary factors associated with renal stone formation were analyzed and the relative urinary supersaturation of calcium oxalate, calcium phosphate (brushite), sodium urate, struvite and uric acid were calculated.ResultsUrinary composition changed during flight to favor the crystallization of calcium-forming salts. Factors that contributed to increased potential for stone formation during space flight were significant reductions in urinary pH and increases in urinary calcium. Urinary output and citrate, a potent inhibitor of calcium-containing stones, were slightly reduced during space flight. Dietary intakes were significantly reduced for a number of variables, including fluid, energy, protein, potassium, phosphorus and magnesium.ConclusionsThis is the first in-flight characterization of the renal stone forming potential in astronauts. With the examination of urinary components and nutritional factors, it was possible to determine the factors that contributed to increased risk or protected from risk. In spite of the protective components, the negative contributions to renal stone risk predominated and resulted in a urinary environment that favored the supersaturation of stone-forming salts. Dietary and pharmacologic therapies need to be assessed to minimize the potential for renal stone formation in astronauts during/after space flight. |
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