The Urologist’s Guide to the Galaxy.

“Far out in the uncharted backwaters of the unfashionable end of the Western Spiral arm of the Galaxy....” Stone disease has affected mankind since earliest recorded history and will trouble us as we strive for the stars. Zero and microgravity are risk factors for urolithiasis, but the incidence is not yet known. Yet, the possible “century of space exploration” lies before us if payloads can be inexpensively offloaded from Earth’s surface to orbit. The scientific publications about medical conditions of astronauts, deep water environments (submarine) and extreme conditions (Arctic and Antarctic) were reviewed to better understand the urologic risks. Actual events were next sought and any scientific data regarding therapeutic intent was carefully scrutinized. Incidence and risk potential could then be calculated and potential for intervention would then be known. The National Space Biomedical Research Institute has classified space health hazards and stone disease as “Risk 12.” Combined statistics from NASA’s Gemini, Apollo, and Space Shuttle flights and long-term missions such as Shuttle-Mir or Skylab fail to reveal any “disclosed” emergency stone events. One published article suggests that some cosmonauts have in fact formed stones during space missions. Detailed data from 79 U.S. space missions, involving 219 person-flights, and 175 astronauts show 23 genitourinary problems (1.2 % or 0.07 incidence for 7 days). Submarine encounters are different, however, with 1.8 to 2.6 actual emergency evacuations per 1,000 person months and 23 kidney stone events (data from all subs in U.S. Atlantic Fleet 1993–1996). Extreme environment data appears more similar to that of spaceflight (despite full Earth’s gravity) with 1,967 person-years distribution showing no definite stone formation/evacuation (but 335 or 3.6% were not-specified). Pak and co-workers at the University of Texas, Southwestern have extensively evaluated the metabolic consequences of bone-mineral loss and urinary parameters associated with the increased risk of stone formation in space. Astronauts are at significantly greater risk of forming calcium oxalate, calcium phosphate and uric acid stones, and this persists for a period of time following return to normal gravity. Conflicting data exists regarding submarine and extreme environmental databases as to the “actual” space mission risks but the hazard is real. Attempts to evaluate both diagnostic and therapeutic interventions are being pursued. As the number of space visitors increases, so should the incidence of urolithiasis. Both diagnostic and therapeutic methods need to be developed coincident to our further efforts in space. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]