In high altitudes erythrocyte levels go up will these stay the same?

No, the erythrocyte levels will not stay the same. At high altitudes, the body produces more erythrocytes (red blood cells) in order to carry more oxygen to the body's tissues. This is because the air at high altitudes is thinner, so there is less oxygen available to breathe. The body compensates for this by increasing the number of red blood cells, which carry oxygen from the lungs to the rest of the body.

When a person returns to a lower altitude, the body will gradually reduce the number of erythrocytes. This is because there is more oxygen available at lower altitudes, so the body does not need as many red blood cells to carry oxygen. The process of reducing the number of erythrocytes can take several weeks or months.