Fictional composite case
This case is invented for teaching. It combines typical features from the cited sources and describes no real astronaut, spaceflight participant or patient. No real patient data were used.
Case File: Flank Pain in Month Five
Gravity FieldsDistance from EarthHostile/Closed EnvironmentRenal & GUMusculoskeletalIn-flightLEO long-durationMars transit & surfaceLunar surfaceClinicianOperator / SFP
- Spaceflight raises stone risk through bone calcium loss and lower urine volume [1]. ◆◆◆◆ High · F
- No symptomatic stones have been reported in U.S. ISS crew to date, but risk after flight is estimated at 2–7 times preflight [1]. ◆◆◇◇ Low · F C
- Prevention is mainly fluids; potassium citrate reduced risk markers in a flight study [1][4]. ◆◆◆◇ Moderate · F C
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.
Presentation
In month 5 of a 6-month mission, a 44-year-old crewmember develops sudden, severe left flank pain that comes in waves and spreads toward the groin. He is nauseated and has vomited once. A crew medical officer (CMO), who is not a physician, examines him with the ground flight surgeon on a video link.
- Background: one kidney stone at age 30, disclosed before flight. His logged fluid intake has averaged about 1.5 L a day.
- Findings: no fever. Urine dipstick shows blood.
- Equipment on board: ultrasound, pain and nausea medicines, intravenous fluids.
Questions
- Why is the risk of kidney stones higher in spaceflight?
- How would the diagnosis be made on board?
- What is the key management decision?
- How could this have been prevented?
Think through your answers before opening the reveals below.
Reveal
Question 1: answer and discussion
Why is the risk of kidney stones higher in spaceflight?
- Bone loss releases calcium, which is excreted in the urine [1][2].
- Less urine. In long-duration crew, urine volume was 47% lower before flight day 30 and 39% lower after flight day 60 [1].
- Urine chemistry. Supersaturation of stone-forming salts (brushite and calcium oxalate) rose during flight [1][2].
- A prior symptomatic stone is a clear personal risk factor [1].
Question 2: answer and discussion
How would the diagnosis be made on board?
With ultrasound, which is NASA’s in-flight diagnostic tool for this problem [1]. A non-physician crewmember can obtain usable images when guided in real time by experts on the ground. See point-of-care ultrasound. Look for hydronephrosis and a stone.
NASA notes an open question: whether ultrasound criteria work the same way in flight. For example, cabin carbon dioxide may weaken the “twinkle” artifact used to spot stones [1].
Question 3: answer and discussion
What is the key management decision?
Treat pain and nausea and give fluids. The key decision is whether he can be managed on board or needs evacuation:
- Red flags: fever (possible infected, blocked kidney), little or no urine, or pain and vomiting that cannot be controlled.
- In low Earth orbit, evacuation to Earth is the backstop for conditions beyond onboard capability. NASA standards put preservation of life ahead of the mission [3].
- On a Mars mission there would be no evacuation; a stone in transit could threaten the mission, so ultrasound and drugs on board must be enough [1].
For context: NASA reports no symptomatic kidney stones in U.S. ISS crew to date, and one possible episode in a cosmonaut [1]. How best to treat a blocking stone in flight without evacuation (for example, by ultrasound-guided stone repositioning) is pending verification.
Question 4: answer and discussion
How could this have been prevented?
- Fluids. Stone risk rises when urine output falls below 1.5 L a day. A NASA model suggests water intake would need to rise to about 3.2 L a day to bring calcium oxalate risk back to preflight levels [1].
- Potassium citrate. In a flight study of 30 crewmembers, 20 mEq a day reduced calcium oxalate risk markers [4].
- Diet. Limit sodium and animal protein [1].
- Protect bone with resistance exercise, which reduces the calcium released into urine [1].
With his stone history, a preflight urology review and 24-hour urine test would have been reasonable; see kidney stone risk.
Teaching points
- Bone loss plus low urine volume makes spaceflight a stone-forming environment [1].
- Ultrasound, operated by crew with remote guidance, is the in-flight diagnostic tool [1].
- Distance changes the decision: evacuation is possible from low Earth orbit, but not from a Mars transit [3][1].
- Hydration is the main countermeasure; citrate is an option for high-risk crew [1][4].
- Stone risk stays higher for about a year after return, at an estimated 2–7 times the preflight rate [1].
Read more
Evidence profile
- Overall certainty
- ◆◆◇◇ Low (proposed)
- Evidence types
- F · Flight dataC · ComputationalE · Expert / operational / standards
- Literature through
- 2026-10-14
- Case data
- Fictional composite; no real patient data
- Credit
- Educational only; no CME or other credit
Requirements referenced 4
| Requirement | Title | Plain-language meaning |
|---|---|---|
| [V1 3004] | In-Mission Medical Care | Training, capabilities and resources to diagnose and treat conditions, based on risk assessment and mission constraints. |
| [V1 3007] | Medical Evacuation | Evacuation to a higher level of care for conditions beyond onboard capability; preservation of life comes first. |
| [V1 4019]–[V1 4020] | Nutritional Status / In-Mission Nutrient Intake | Diet assessed and must meet 100% of nutrient and energy needs. |
| [V2 7045] | Medical Equipment Usability | Medical equipment usable by non-physicians. |
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 4
- NASA Human Research Program. Evidence Report: Risk of Renal Stone Formation (2024). humanresearchroadmap.nasa.gov/evidence/other/2024%20Renal%20… NASA F
- Smith SM, Heer M, Shackelford LC, 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
- NASA OCHMO. NASA-STD-3001, Volume 1: Crew Health, Revision C (2023). www.nasa.gov/wp-content/uploads/2023/11/nasa-std-3001-vol-1-… Standard E
- Whitson PA, Pietrzyk RA, Jones JA, Nelman-Gonzalez M, Hudson EK, Sams CF. 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 was fetched, each DOI's title/journal/year matched via Crossref, PubMed IDs matched to DOIs, and claims were checked against the source text (abstract, NASA document or official web 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
- Authors
- Pending (AI-assisted draft)
- Reviewer
- Pending review
- Last reviewed
- Pending review
- Literature through
- 2026-10-14
- AI-assisted
- Yes (disclosed)
- COI
- Pending
- License
- CC BY-SA 4.0
- Use
- Educational only · no CME credit · Disclaimer
- Cite this version
- Pending first edition
Educational use only · not medical advice · Disclaimer · CC BY-SA 4.0