Effect of potassium citrate therapy on the risk of renal stone formation during spaceflight.
OBJECTIVE
Exposure to microgravity affects human physiology and results in changes in urinary chemical composition during and after spaceflight, favoring an increased risk of renal stones. We assessed the efficacy of potassium citrate to decrease the stone risk during and after spaceflight.


METHODS
The study was done in 30 long duration spaceflight crew members to the space stations Mir and International Space Station. Before, during and after spaceflight 24-hour urine samples were collected to assess the renal stone risk. Potassium citrate (20 mEq) was ingested daily by International Space Station crew members in a double-blind, placebo controlled study. Mir crew members performed the identical protocol but did not ingest medication.


RESULTS
Potassium citrate treated crew members had decreased urinary calcium excretion and maintained the calcium oxalate supersaturation risk at preflight levels compared to that in controls. Increased urinary pH in the treatment group decreased the risk of uric acid stones.


CONCLUSIONS
Results from this investigation suggest that supplementation with potassium citrate may decrease the risk of renal stone formation during and immediately after spaceflight.
Whitson
Peggy A
PA
Astronaut Office, National Aeronautics and Space Administration Johnson Space Center, Houston, Texas, USA.
Pietrzyk
Robert A
RA
Jones
Jeffrey A
JA
Nelman-Gonzalez
Mayra
M
Hudson
Edgar K
EK
Sams
Clarence F
CF
D000328:Adult; D005260:Female; D006801:Humans; D007669:Kidney Calculi / Q000517:prevention & control*; D008297:Male; D019357:Potassium Citrate / Q000627:therapeutic use*; D012307:Risk Factors; D013026:Space Flight
D019357:Potassium Citrate