Final answer:
The condition described with a low hematocrit and hemoglobin level is anemia, which involves insufficient red blood cells and affects oxygen delivery to the body.
Step-by-step explanation:
When the expansion of plasma volume is greater than the mass of red blood cells (RBCs) leading to changes in blood/plasma composition and a hematocrit less than 30% or hemoglobin less than 10 g/dL, the condition is characterized as anemia.
Anemia results from inadequate production, excessive destruction, or loss of red blood cells, which subsequently decreases their number or hemoglobin content, compromising the oxygen delivery to body tissues. This can cause various symptoms, such as fatigue, lethargy, and increased risk for infection due to the tissues' reduced oxygen levels.
Anemia contrasts with polycythemia, an elevated RBC count that can arise from dehydration, high-altitude residence, or rare conditions like polycythemia vera. It is essential to differentiate between these conditions as they require different therapeutic approaches.