Kidney stones
Also: Renal Stone risk
Gravity FieldsHostile/Closed EnvironmentRenal & GUIn-flightPostflight RecoveryLEO long-durationLunar surfaceMars transit & surfacePublicClinicianResearcher
- Kidney stone risk rises in flight, driven by bone calcium and low urine volume. Higher fluid intake is the simplest countermeasure. ◆◆◆◇ Moderate · F
- Potassium citrate kept stone-forming chemistry at preflight levels in a placebo-controlled flight study. ◆◆◆◇ Moderate · F
- A stone can't yet be treated on a deep-space mission. NASA rates the Mars risk 4×4, requiring mitigation. ◆◆◆◆ High · E
Proposed certainty (◆ High → ◇ Very low) and evidence-type tags: F flight · A analog · M model/animal · C computational · E expert/operational/standards. AI-proposed, pending reviewer confirmation. How to read the grades.
NASA risk title (verbatim)
Risk of Renal Stone Formation
NASA short title: Renal Stone · HRP element: Exploration Medical Capability (ExMC) · Status: Active [current research ongoing] [1]
What it is
Astronauts can develop symptomatic kidney stones in flight and after flight [1]. Calcium released from bone, together with low urine volume, makes stones more likely [4].
Current evidence
- Ways to reduce risk are well defined, but there is not yet any way to treat a stone during an exploration mission [1].
- On 4- to 6-month ISS missions, stone risk rose regardless of exercise device. Low urine volume was a key factor, so drinking more fluid is the easiest mitigation [4].
- In 30 Mir and ISS crew members, daily potassium citrate lowered urinary calcium and kept calcium oxalate stone risk at preflight levels compared with controls [5].
- Ground studies show exercise lowers urinary calcium, so NASA counts it as a valid countermeasure [1].
NASA’s risk posture
NASA scores each risk for each design reference mission (DRM) as likelihood × consequence (LxC). Both run from 1 (lowest) to 5 (highest) on the HSRB’s 5×5 matrix [1][3]. Each score comes with a disposition, such as “Accepted”, “Requires Characterization” or “Requires Mitigation”. These ratings were last approved by NASA’s Human System Risk Board (HSRB) in 4/2022 [1].
| Mission | Duration | In-mission (operations) | Long-term health |
|---|---|---|---|
| LEO | Short (under 30 d) | 1x4 · Accepted with Monitoring | 1x3 · Accepted with Monitoring |
| LEO | Long (30 d–1 yr) | 3x4 · Accepted with Monitoring | 2x3 · Accepted with Monitoring |
| Lunar orbit | Short | 1x4 · Accepted with Monitoring | 1x3 · Accepted with Monitoring |
| Lunar orbit | Long | 3x4 · Accepted with Monitoring | 2x3 · Accepted with Monitoring |
| Lunar orbit + surface | Short | 1x4 · Accepted with Monitoring | 1x3 · Accepted with Monitoring |
| Lunar orbit + surface | Long | 3x4 · Accepted with Monitoring | 2x3 · Accepted with Monitoring |
| Mars preparatory | Under 1 yr | 3x4 · Requires Mitigation | 3x4 · Requires Mitigation |
| Mars planetary | 730–1,224 d | 4x4 · Requires Mitigation | 4x4 · Requires Mitigation |
Copied from the Human Research Roadmap on 2026-10-14. Ratings change. Check the live record before citing.
Open knowledge gaps
NASA lists 1 knowledge gaps for this risk, 1 of them open as of 2026-10-14 [1]. Each gap ID links to its page on the Human Research Roadmap (HRR).
Show NASA’s gap list (verbatim)
| Gap | NASA gap statement | Status |
|---|---|---|
| Renal-101 | We do not have the capability to mitigate renal stones in spaceflight. | Open |
See also Open questions.
Active countermeasure research
- Current research. This aims to (1) build in-flight stone prevention into exploration medical systems, (2) detect stones early with increasingly autonomous ultrasound and biochemical tests, and (3) treat them, for example by moving stones with focused ultrasound [1].
Project-level detail, including status, investigators and results, is in the NASA Task Book and on each HRR gap page.
Clinical articles
For practical, clinic-facing guidance, see:
Evidence profile
- Overall certainty
- ◆◆◆◇ Moderate (proposed)
- Evidence types
- F · Flight dataA · Terrestrial analogE · Expert / operational / standards
- Literature through
- 2026-10-14
- NASA source
- Human Research Roadmap risk page (last published 05/13/25; read 2026-10-14)
Requirements referenced 2
| Requirement | Title | Plain-language meaning |
|---|---|---|
| [V2 6109] | Water Quantity | Vehicles must provide enough potable water for crew needs. |
| [V1 4027] | In-Mission Bone Mineral Density Maintenance | Countermeasures must keep total hip and lumbar spine BMD at ≥95% and femoral neck ≥90% of preflight. |
IDs as published in NASA-STD-3001 Vol. 1 Rev C (2023-09-15) and NASA-STD-3001 Vol. 2 Rev F (2026-07-14). NASA-STD-3001 binds NASA programs; it is not a regulation for commercial flights. Paraphrased. Standards quick reference.
References 5
- NASA Human Research Roadmap. Risk record: “Risk of Renal Stone Formation”. Accessed 2026-10-14. humanresearchroadmap.nasa.gov/Risks/?i=81 NASA E
- NASA Human Research Program. Evidence report for the Renal Stone risk (approved September 23, 2024). humanresearchroadmap.nasa.gov/evidence/other/2024%20Renal%20… NASA E
- Antonsen EL, et al. Updates to the NASA human system risk management process for space exploration. NPJ Microgravity. 2023;9:72. doi:10.1038/s41526-023-00305-z PMID:37679359 Peer-reviewed E
- Smith SM, et al. Bone metabolism and renal stone risk during International Space Station missions. Bone. 2015;81:712–720. doi:10.1016/j.bone.2015.10.002 PMID:26456109 Peer-reviewed F
- Whitson PA, et al. Effect of potassium citrate therapy on the risk of renal stone formation during spaceflight. J Urol. 2009;182(5):2490–2496. doi:10.1016/j.juro.2009.07.010 PMID:19765769 Peer-reviewed F
Machine-checked on 2026-10-14: each URL resolved, each DOI's title/journal/year matched via Crossref, and claims were checked against the source text (abstract or full NASA page). Human verification against full text is still required before review. NASA documents are U.S. Government works (public domain) and are summarized with attribution; journal articles are summarized, not reproduced.
Article info
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- Last reviewed
- Pending review
- Literature through
- 2026-10-14
- AI-assisted
- Yes (disclosed)
- COI
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- License
- CC BY-SA 4.0
- Use
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- Cite this version
- Pending first edition