In space, microgravity reduces the overload on bones and promotes bone resorption (bone dissolution), which increases the risk of urinary stone formation by excreting calcium dissolved from the bones into the urine.The pain caused by urinary stones is one of the "three major pains in the world" and is one of the "three major pains in the world". There is a risk of doing so.

　In a long-term lying test that modeled space (micro-gravity environment) in 2008, Associate Professor Okada and colleagues reported that bisphosphonates, a therapeutic agent for osteoporosis that suppresses bone resorption, could prevent calculus formation.Based on this, we asked astronauts to take bisphosphonates during their stay at the International Space Station for about 6 months, and examined their effects.

　First, we confirmed that the administration of bisphosphonates was effective in maintaining bone density in astronauts, and announced it in 2019.In a subsequent study, we found that administration of bisphosphonates reduced multiple urinary stone risk factors as well as bone resorption.In astronauts who did not take bisphosphonate, urinary excretion of calcium from bone increased with the start of space flight, and the urinary tract, which is a decomposition product of the bone matrix protein "type I collagen" and is similar to calcium. Urinary excretion of the stone risk factors "oxalic acid" and "lactic acid" increased, while urinary excretion of both bisphosphonates decreased significantly.

　This study succeeded in showing that bone resorption inhibitors suppress the increase in bone resorption during space flight and reduce the risk of urinary stones.It was suggested that bisphosphonates may be a new treatment for urinary stone formation even on the ground.

Paper information:[JBMR Plus] Bisphosphonate Use May Reduce the Risk of Urolithiasis in Astronauts on Long-Term Spaceflights