RBC Count

Function

The Red Blood Cell (RBC) count measures the number of erythrocytes in a microliter of whole blood. RBCs contain hemoglobin, the protein responsible for transporting oxygen from the lungs to the body's tissues and carrying carbon dioxide back to the lungs for excretion. Maintaining an optimal number of RBCs is critical for aerobic metabolism and cellular energy production.

Why it is Ordered

An RBC count is a standard component of the Complete Blood Count (CBC). It is ordered during routine physicals, prior to surgery, and to investigate symptoms such as chronic fatigue, weakness, shortness of breath, or pale skin (pallor). It is also essential for monitoring patients with known blood disorders, kidney disease (as kidneys produce erythropoietin), or those undergoing chemotherapy.

Associated Conditions

• Anemia (Low RBC): Can result from iron, B12, or folate deficiency, chronic bleeding, bone marrow suppression, or hemolytic diseases where RBCs are destroyed prematurely.
• Polycythemia (High RBC): May be 'primary' (Polycythemia Vera, a bone marrow disorder) or 'secondary' due to chronic hypoxia. Secondary polycythemia is common in heavy smokers, patients with COPD, or those living at high altitudes, as the body produces more RBCs to compensate for lower oxygen levels.