Altitude Check

Important — about this tool

Altitude Check is a pre-travel risk awareness tool, not a validated clinical diagnostic instrument. The risk scoring algorithm is an educational model built on established risk factors documented in peer-reviewed altitude medicine literature. The relative weightings assigned to each factor are informed by the clinical evidence below, but the specific point values are the tool's own construction and have not been independently validated.

For clinical diagnosis of AMS after arrival at altitude, doctors use the Lake Louise Score — a validated instrument developed at the 1991 International Hypoxia Symposium. Altitude Check serves a different purpose: helping travellers understand their risk before departure so they can prepare appropriately.

If your result is moderate or high risk, or if you have any pre-existing health conditions, please consult a travel medicine doctor before travelling to high altitude. A pre-travel consultation 4–6 weeks before departure is standard practice.

Key statistics & their sources

36.7% AMS prevalence in Lhasa

Honigman, B., Theis, M.K., Koziol-McLain, J., et al. (1993). Acute mountain sickness in a general tourist population at moderate altitudes. Annals of Internal Medicine, 118(8), 587–592. Cross-referenced with Wu, T. et al. studies on Han and Tibetan populations at 3,658m.

Oxygen availability calculation

Calculated using the standard barometric pressure exponential decay formula: O₂% = 100 × e^(−altitude/7400). This is a well-established atmospheric physics approximation used throughout altitude medicine literature. Accurate to within ±2–3% for practical purposes across typical trekking altitudes.

AMS risk begins at 2,500m

Luks, A.M., McIntosh, S.E., Grissom, C.K., et al. (2010). Wilderness Medical Society Consensus Guidelines for the Prevention and Treatment of Acute Mountain Sickness. Wilderness & Environmental Medicine, 21(2), 146–155. This is the primary clinical reference for AMS risk thresholds used throughout this tool.

Ascent rate guideline — 300–500m per day above 3,000m

Wilderness Medical Society Consensus Guidelines (Luks et al., 2010, above). Corroborated by Bartsch, P., & Swenson, E.R. (2013). Acute high-altitude illnesses. New England Journal of Medicine, 368, 2294–2302.

Acetazolamide (Diamox) as AMS preventative

Sartori, C., Allemann, Y., Duplain, H., et al. (2002). Acetazolamide for prevention of acute mountain sickness: a double-blind, randomised, placebo-controlled trial. BMJ, 325, 1492. Also: Wilderness Medical Society Consensus Guidelines (Luks et al., 2010).

HACE and HAPE as severe altitude illness

Hackett, P.H., & Roach, R.C. (2001). High-altitude illness. New England Journal of Medicine, 345(2), 107–114. This remains one of the most cited overviews of altitude illness in clinical medicine.

Lake Louise Score — the validated clinical diagnostic instrument

Roach, R.C., Bartsch, P., Hackett, P.H., & Oelz, O. (1993). The Lake Louise acute mountain sickness scoring system. In: Sutton, J.R., Houston, C.S., Coates, G. (eds). Hypoxia and Mountain Medicine. Burlington, VT: Queen City Printers, 272–274. Altitude Check is distinct from this validated instrument — it is a pre-travel educational tool, not a diagnostic score.

Risk factors included in the scoring model

The following risk factors are included in the Altitude Check scoring model. Each is supported by the altitude medicine literature as a clinically recognised risk modifier for AMS:

Peak altitude
Primary determinant — risk rises significantly above 2,500m and again above 3,500m, 4,000m and 5,000m.

Prior altitude experience
Previous susceptibility is the strongest individual predictor of future AMS episodes.

Ascent rate
How quickly you gain altitude is the most controllable risk factor. Slow ascent is the primary prevention strategy.

Sleep quality
Poor sleep raises cortisol and impairs acclimatisation. Cheyne-Stokes breathing at altitude worsens existing sleep problems.

Hydration & alcohol
Dehydration worsens AMS symptoms. Alcohol suppresses the hypoxic ventilatory response and disrupts sleep at altitude.

Smoking status
Chronic smoking impairs pulmonary function and reduces reserve capacity for the hypoxic stress of altitude.

Age
Modest association — older travellers have slightly elevated risk, though fitness and health status are stronger predictors.

Pre-existing conditions
Cardiac and pulmonary conditions, anaemia, and diabetes all reduce the body's capacity to compensate for hypoxia at altitude.

Note on fitness: Physical fitness has a limited protective effect against AMS. Cardiovascular fitness does not predict acclimatisation capacity. Elite athletes develop AMS at the same rates as non-athletes at equivalent altitudes. This is counterintuitive but well-documented in the literature and reflected in the tool's modest weighting for this factor.

References last reviewed: June 2026. Tool version 1.0.

Built in Perth, Western Australia · altitudecheck.com.au

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