Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism

This chapter includes diseases affecting blood components — red blood cells, white blood cells, platelets — and disorders of the immune system. Examples include anemia (such as iron deficiency anemia), clotting disorders like hemophilia, and platelet abnormalities. It also covers bone marrow disorders and certain autoimmune conditions that affect blood formation.
Immune mechanism disorders are also coded here, including immunodeficiency states (like inherited immune deficiencies) and autoimmune diseases that do not fall under other system chapters. Some conditions like sickle cell disease and thalassemia are included because they involve abnormal hemoglobin.
These codes are important for hematology, oncology, and chronic disease management. Blood disorders often affect oxygen transport, infection resistance, or clotting ability, which can significantly impact overall health. This chapter separates primary blood diseases from secondary manifestations caused by other systemic conditions.