Two identical twin boys are separated for a year. One lives at sea level, and the other lives in the mountains, at about a 7000-ft elevation. Assuming neither has any episode of bleeding, and both are fed an equivalent diet, what could you conclude about the red blood cell mass of each of the boys?

Question

Quizplus · Accepted Answer

Red blood cell production increases at lower inspired oxygen concentrations. The boy living at high altitudes would have a greater hypoxic stress to produce red blood cells and would, compared to his twin, have a relative erythrocytosis. Similarly, a person with a history of chronic obstructive lung disease and chronic hypoxemia would be expected to have a higher red blood cell count than a person who does not smoke or never has smoked.

Two Identical Twin Boys Are Separated for a Year