However, CMS is also considered an adaptation of pulmonary and heart disease to life under chronic hypoxia at altitude.Consensus for clinical diagnosis of CMS use laboratory values: haemoglobin in Males ≥ 21 g/dL; Females ≥ 19 g/dL, haematocrit > 65%, and arterial oxygen saturation (SaO2) < 85% in both genders. Treatment
Migration to low altitude is curative, though not immediate, as the body adapts to the normal oxygen level near sea-level and the haematocrit normalises. Alternatively, bloodletting (phlebotomy) can be performed to lower the haematocrit temporarily; when combined with volume replacement with fluids this can have a longer effect.Medication with acetazolamide, a carbonic anhydrase inhibitor, has been shown to improve chronic mountain sickness by reducing erythropoietin and the resulting polycythaemia, which results in better arterial oxygenation and a lower heart rate.Oxygen therapy and training in slow breathing techniques has been shown to reduce symptoms through increasing blood oxygenation. Epidemiology
Although CMS generally affects people native to altitudes higher than 3,000 metres (9,800 ft), it does not affect populations around the world equally. A 2013 study reviewed CMS prevalence rates around the world and found the highest rates were found in Andean countries of South America and the lowest rates in people native to the East African Mountains of Ethiopia.
CMS prevalence rates reported from the study are summarised below:

Ethiopia [3600–4100 m]: 0%
Tibetan Plateau (Tibetans): 0.91–1.2%
Indian Himalayas [3000–4200 m]: 4–7%
Kyrgyzstan [3000–4200 m]: 4.6%
Tibetan Plateau (Han Chinese): 5.6%
La Paz, Bolivia [3600 m]: 6% to 8%
Bolivia: 8–10%
Cerro de Pasco, Peru [4300 m]: 14.8–18.2%

References
External links

^  Online calculator illustrating blood oxygen carrying capacity at altitude