Answer
Normal hematocrit for health adult males at seal level is 42-54%. For females it is 38-46%.
At high altitude the pO2 of oxygen drops because the atmospheric pressure falls lower and lower as one ascends higher. altitudes near or above 6000 meters the body finds it difficult to obtain enough oxygen. This is first detected by the carotid bodies. A number of compensatory mechanisms are activated by the body make adequate amounts of oxygen available to the tissues. The result is that plasma volume increases but the number of RBCs increases. These two effects produce a kind of polycythemia which shows in test as an increase in hematocrit . A male who is acclimated to high altitude (6,000 to 9,000 feet) will have a hematocrit of about 45-61%.
Work Step by Step
As one ascends to higher and higher altitude , one comes into zones of lower and lower atmospheric pressure. The percentage of oxygen in the air remains at 20.9% but the pO2 of oxygen (21.36pKa) falls. As a consequence less oxygen is absorbed in the lungs and the oxygen level in the blood decreases. The carotid bodies of the aorta and carotid arteries are quick to detect the relative rise in CO2 and the body sets in motion several compensatory mechanisms to ensure adequate supply of oxygen to the brain and heart. The compensatory changes include increases in heart rate(HR), respiratory rate(RR), and in stroke volume(SV). In the short run ( 18-25 days) at 6000+ feet, the following changes will accompany the altitude acclimation process: plasma volume will fall;, hematocrit will rise and the number of RBCs will increase. Later, new capillaries will grow and there will be increased myoglobin synthesis in muscles.
