Which of the following is a common cause of a high red blood cell count?

• A. Anemia
• B. Dehydration
• C. Bacterial infection
• D. Viral infection

Answer: (B)

A high red blood cell count often comes from hemoconcentration due to dehydration. When fluid volume in the bloodstream drops, the concentration of red cells increases, so the counts appear higher even though the total red cell mass hasn’t changed. This is known as relative polycythemia. Anemia would reduce red cells, not raise them. Infections, whether bacterial or viral, don’t commonly cause a rise in red cell count; they affect other parts of the blood profile, such as white cells or inflammatory markers, much more than the red cell number. If dehydration is suspected, rechecking after rehydration or assessing hydration status alongside hematocrit and hemoglobin helps confirm the cause.