Why doctors do test on red blood cells?

Doctors perform tests on red blood cells (RBCs) to assess various aspects of a patient's health, including oxygen-carrying capacity, anemia, and overall blood function. Common tests, such as a complete blood count (CBC), measure parameters like hemoglobin levels, hematocrit, and RBC count to help diagnose conditions such as infections, nutritional deficiencies, and bone marrow disorders. Analyzing RBCs can also provide insights into chronic diseases and guide treatment decisions.