Final answer:
Polycythemia is diagnosed by an elevated RBC count and hematocrit, indicating increased blood viscosity. Dehydration, high-altitude living, and the bone marrow disease polycythemia vera are common causes. Polycythemia vera is most prevalent in males over 60 and can raise blood pressure by thickening the blood.
Step-by-step explanation:
Polycythemia is usually diagnosed through the detection of an elevated red blood cell (RBC) count and a resulting increase in hematocrit. This condition indicates that the blood has become more viscous, making it harder for the heart to pump blood throughout the body, which can dangerously raise blood pressure. There are various causes of polycythemia, such as dehydration, where the plasma volume decreases due to inadequate water intake or excessive water loss, leading to a rise in hematocrit temporarily. Another cause is living at high altitudes, where a mild form of polycythemia is considered normal due to the chronic low oxygen environment, which stimulates RBC production. Additionally, some elite athletes train at high altitudes to intentionally induce this effect for improved athletic performance. However, a more severe and pathological form of polycythemia is called polycythemia vera, which is a bone marrow disease leading to excessive production of immature erythrocytes. Most commonly seen in elderly patients, particularly those over 60 years of age, polycythemia vera is more prevalent in males and increases the blood's viscosity to potentially dangerous levels.