Final answer:
An increase in hemoglobin and hematocrit in a client with COPD is primarily due to elevated levels of erythropoietin, which stimulates the production of more erythrocytes to enhance the blood's oxygen-carrying capacity in response to chronic low oxygen levels.
Step-by-step explanation:
The increase in hemoglobin and hematocrit in a client with chronic obstructive pulmonary disease (COPD) is usually due to elevated levels of erythropoietin (EPO). In the setting of COPD, where chronic hypoxemia occurs, the kidneys are stimulated to produce greater amounts of EPO. This hormone promotes the production of erythrocytes (red blood cells), leading to an increased number of circulating erythrocytes and, consequently, higher hemoglobin levels. Increased erythrocyte count is a compensatory mechanism to increase the oxygen-carrying capacity of the blood when chronic low oxygen levels are present.
An increase in hematocrit and hemoglobin is generally not due to improved oxygenation from increased lung function in COPD, rather it's a response to chronic low oxygen levels. Conditions like dehydration can also lead to hemoconcentration, which might temporarily raise hematocrit levels, but this is different from the chronic erythropoietic response seen in COPD. Similarly, reduced production of red blood cells and diseases such as polycythemia vera can affect blood viscosity and erythrocyte count, but these are not typically associated with the response observed in COPD.