A hematocrit level (volume of red blood cells in the blood) greater than 80%, 8 liters of blood when the average is 5, permanently hyperdilated blood vessels, not counting the right ventricle of the enlarged heart… All workers in the gold mine of La Rinconada (southeast of Peru), the highest city in the world (5,300 meters), examined in February 2019 by a French team present this frightening table that would precipitate any inhabitant of the plains to emergencies. To endure hypoxia – 50% less oxygen than sea level – all live at the limit of the human body’s capabilities, even if not all of them feel sick.
This is the main result revealed by the head of the expedition, Samuel Vergès, from the Hypoxia and physiopathology laboratory (HP2, Inserm and Grenoble-Alpes University). A year ago, the twelve scientists on his team set up an ephemeral laboratory offering a battery of blood, respiratory and genetic tests in La Rinconada, a pseudo-city born of a gold rush, where more than 50,000 survive. inhabitants without running water or mains drainage and almost no doctors.
At such an altitude, where it was thought permanent human life impossible, only a quarter of the population shows signs of chronic mountain sickness
The researchers wanted to understand why at such an altitude, where it was thought that permanent human life was impossible, only a quarter of the population showed signs of chronic mountain sickness or CMS (chronicle mountain sickness). A syndrome that includes several symptoms: headache, shortness of breath, palpitations, cyanosis, paraesthesia, tinnitus, sleep disturbance and vascular disorders. But today, after analyzing 80% of the data, the team must admit that they have not yet solved the puzzle. " At 5,300 meters, we expected to find physiological differences between people with CMS and others, as we observe at 4,000 meters, but there are none. ", Notes Samuel Vergès who specifies:" At 4000 meters, Peruvians in the mountains usually trigger a CMS when their hematocrit rate exceeds 63%. It’s a pretty reliable marker. At 5,000 meters, all are more than 80% without necessarily experiencing mountain sickness. "
In other words, we still don't know why some people have this chronic disease and others don't. This could be due to genetic or epigenetic differences which are also the subject of the Grenoble program, but the analyzes are not finished. Another hypothesis is that people who have not yet declared a CMS end up making one, sooner or later. Because all the analyzes show that their organism, in permanent fight against hypoxia, has reached the limits of the bearable. All of them make a huge amount of red blood cells, their blood becomes very viscous and their vessels have to dilate as much as possible to drain it, which leaves no room for maneuver in the event of a stroke. To supply the pulmonary system, which also suffers from lack of oxygen, the ventricle is overheated, hence its enlarged shape. Finally, blood tests reveal a permanent inflammatory state and oxidative stress. In other words, even those who don't have CMS live on the brink of a serious ischemic attack.