Renal Stone Risk During Spaceflight: Assessment and Countermeasure Validation (Renal Stone)
Research Area: Integrated Physiology and Nutrition
Expeditions: 3-6, 8, 11- 14
Principal Investigator(s): ● Peggy A. Whitson, PhD, Johnson Space Center, Houston, Texas
RESEARCH OBJECTIVES
The Renal Stone experiment collects urine samples from crew members and tests a possible
countermeasure for preventing kidney stone formation.
EARTH BENEFITS
Understanding how the disease may form in otherwise healthy crew members under varying
environmental conditions provides insight into stone-forming diseases on Earth.
SPACE BENEFITS
Human exposure to microgravity results in a number of physiological changes. Among these are
changes in renal function, fluid redistribution, bone loss, and muscle atrophy, all of which
contribute to an altered urinary environment and
the potential for renal stone formation during
and immediately after flight. In-flight changes
previously observed include decreased urine
volume and urinary citrate and increased urinary
concentrations of calcium and sodium. The
formation of renal stones could have severe
health consequences for crew members and
negatively impact the success of the mission. This
study gives a better understanding of the risk
factors associated with renal stone development
during and after flight, as well as test the
effectiveness of potassium citrate as a
countermeasure to reduce this risk.
RESULTS
The Renal Stone investigation contained 2 sequential sampling groups in its single-trial, 2-phase
design. Phase 1 of the study sampled 12 male astronauts and cosmonauts during NASA-Mir
spaceflights in 129- to 208-day missions and served as a control group with no treatment. Phase
2 collected data from 18 ISS crew members in a double-blind study that included control and
treatment with potassium citrate (K-Cit) pill supplements in 93- to 215-day missions from ISS
Expeditions 3-14. Urine samples were collected and analyzed before, during, and after mission,
as was dietary information from crew members to document urine chemistry and mineral-
nutrient throughput. As a safety measure, all phase 2 participants were K-Cit-tolerance tested
before launch, and none showed any adverse reactions. Renal stones come in the forms of
calcium stones (calcium oxalate (CAOX) and calcium phosphate (Brushite)), uric acid stones, and
ISS013E56052 – ISS Expedition 13 Flight
Engineer Thomas Reiter, seen aboard ISS,
processes samples for the Renal Stone
investigation.