Renal Stone Formation in Spaceflight

The microgravity environment of space increases bone resorption in astronauts, increasing urinary calcium excretion. Dehydration may also occur due to decreased fluid intake and increased fluid loss through insensible losses and space motion sickness. These factors increase the risk of renal stone formation. Renal stones can cause sudden incapacitating pain, requiring immediate treatment. Definitive treatment options are currently unavailable in space, necessitating a return to Earth. Thus, preventative strategies should be employed.

Dietary intake of calcium, oxalate and sodium should be controlled. Citrate intake can help decrease stone formation risk but may not be readily available in space. Potassium-magnesium citrate can be used as a supplement. Exercise and bisphosphonates help significantly mitigate bone mass loss due to microgravity but is inadequate to completely prevent stone formation risk. Thiazides have been trialed with good effect.

Various countermeasures have been investigated for general use and in spaceflight. They can potentially be used to mitigate stone formation risks in future missions. Risk of stone formation can be monitored using urinary biochemistry analyte normograms. These risk mitigation strategies can be employed in the general public to prevent recurrences and manage stone formation risks.