The risk of renal stone formation during and after long duration space flight.
BACKGROUND
The formation of a renal stone during space flight may have serious negative effects on the health of the crewmember and the success of the mission. Urinary biochemical factors and the influence of dietary factors associated with renal stone development were assessed during long duration Mir Space Station missions.


METHODS
Twenty-four-hour urine samples were collected prior to, during and following long duration space flight. The relative urinary supersaturation of calcium oxalate, calcium phosphate (brushite), sodium urate, struvite and uric acid were determined.


RESULTS
Changes in the urinary biochemistry of crewmembers during long duration spaceflight demonstrated increases in the supersaturation of the stone-forming salts. In-flight hypercalciuria was evident in a number of individual crewmembers and 24-hour dietary fluid intake and urine volume were significantly lower. During flight, there was a significant increase in brushite supersaturation.


CONCLUSIONS
These data suggest acute effects of space flight and postflight changes in the urinary biochemistry favoring increased crystallization in the urine. The effects of dietary intake, especially fluid intake, may have a significant impact on the potential for renal stone formation. Efforts are now underway to assess the efficacy of a countermeasure to mitigate the increased risk.
Whitson
P A
PA
NASA/Johnson Space Center, Houston, Tex 77058, USA. peggy.a.whitson1@jsc.nasa.gov
Pietrzyk
R A
RA
Morukov
B V
BV
Sams
C F
CF
D000328:Adult; D002129:Calcium Oxalate / Q000652:urine; D002130:Calcium Phosphates / Q000652:urine; D002951:Citrates / Q000652:urine; D004032:Diet; D006801:Humans; D007669:Kidney Calculi / Q000209:etiology* / Q000517:prevention & control; D008875:Middle Aged; D009751:Nutritional Requirements; D012307:Risk Factors; D013026:Space Flight; D013997:Time Factors; D014556:Urine; D014893:Weightlessness
D002130:Calcium Phosphates; D002951:Citrates; C485828:alpha-tricalcium phosphate; C485830:tetracalcium phosphate; D002129:Calcium Oxalate; C485838:calcium phosphate, monobasic, anhydrous; C020243:calcium phosphate; C485829:calcium phosphate, dibasic, anhydrous