Immunodeficiency due to conditions classified elsewhere

This code signifies an impaired immune system function that is a direct consequence of another underlying disease or condition. It indicates a secondary immunodeficiency, meaning the immune defect is not primary or congenital but acquired due to an external factor or pre-existing illness.

Apply this code when documentation clearly states immunodeficiency is secondary to a specified condition not classified in D80-D83, D84.0, D84.1, D84.9, or B20. Examples include immunodeficiency resulting from malnutrition, chronic renal failure, or certain malignancies. The underlying condition causing the immunodeficiency must also be coded.

• Always sequence the underlying condition first, followed by this code, to accurately reflect the causality.
• Carefully review documentation to ensure the immunodeficiency is explicitly stated as secondary to another condition, not a primary immune disorder.
• Refer to the Excludes1 notes to avoid incorrect co-coding with primary immunodeficiencies or HIV disease.