Question

After the initial surge in EPO on ascent to altitude, approximately how long will red blood cell count remain high?

a) 3 months
b) 1 month
c) 2 weeks
d) 9 months

Answer 1

After an initial increase in EPO due to ascent to high altitude, red blood cell count will typically remain high for about 120 days, which is roughly 4 months, due to the lifespan of erythrocytes.

Step-by-step explanation:

When individuals are exposed to high altitudes, their body compensates for the lower oxygen levels by increasing the production of erythrocytes (red blood cells) through the hormone erythropoietin (EPO). The kidneys produce EPO, which stimulates the formation of red blood cells in the bone marrow. Erythrocytes have a lifecycle of approximately 120 days once they mature from reticulocytes. Therefore, after the initial surge in EPO following ascent to altitude, the red blood cell count will generally remain elevated for the lifespan of these cells, which is around 120 days or about 4 months. This adaptation helps individuals better transport the available oxygen in their bloodstream and perform physical activities with less risk of altitude sickness.