Final answer:
An elevated hematocrit indicates the condition of polycythemia, characterized by an increased volume of red blood cells in the blood, which can be due to dehydration, adaptation at high altitudes, or polycythemia vera, a serious bone marrow disease.
Step-by-step explanation:
An elevated hematocrit constitutes the condition known as polycythemia. When the hematocrit level is high, it means the volume percentage of red blood cells (RBCs) in the blood is increased. This can occur in cases of dehydration, where plasma volume decreases and consequently, hematocrit rises. People living at high altitudes may also have a mild form of polycythemia due to the body's adaptation to lower oxygen levels.
Moreover, a serious bone marrow disease known as polycythemia vera can cause an excessive production of immature erythrocytes, leading to dangerously high blood viscosity. This increased viscosity poses a risk by elevating blood pressure and making it more difficult for the heart to pump blood throughout the body. In contrast, conditions such as anemia involve a deficiency in the number of RBCs or hemoglobin, resulting in decreased ability to deliver oxygen to tissues, and are characterized by symptoms like fatigue and shortness of breath.