When sea level humans go to high altitude, they have to increase their red blood cells in order to compensate for the environment hypobaric hypoxia. What are the normal levels of hemoglobin, hematocrit, and red blood cells for each altitude? What are the specific variations in each civilization? We have over 43 years of work at the high Altitude Pulmonary and Pathology Institute, on this subject. We established the normal values for the city of La Paz, Bolivia at 3522m, in 3373 but it was poorly understood and other centers applied it without considering the variations of altitude. One can take different parameters to evaluate where the top cutoff limit for polyerythrocythemia is and likewise where anemia is present at high altitude. We proposed likewise a classification: Mild, Moderate and Severe, depending on the amount of red blood cells present. The limits where one can speak of polyerythrocythemia, depend on where the symptomatology (if present) appears. But it can also be the standard deviation. The Gauss curve of distribution can also be visually analyzed to set the limits.