D84.81

HCC Category Mapping

What This Code Means

A weakened immune system that develops as a result of another medical condition or disease the patient already has.

Coding Tips

• •Always code the underlying condition first, then use this code as a secondary diagnosis
• •Common underlying causes include malignancy, chronic kidney disease, and autoimmune disorders

Clinical Significance

Immunodeficiency due to conditions classified elsewhere represents secondary immunodeficiency that develops as a consequence of another documented medical condition. Common underlying causes include malignancies (particularly lymphoproliferative disorders), chronic kidney disease with uremia, diabetes mellitus, hepatic cirrhosis, and protein-losing enteropathy, all of which impair immune function through different mechanisms.

Documentation Requirements

• ✓Documentation must identify and code the underlying condition causing the immunodeficiency (malignancy, renal disease, etc.) as the primary diagnosis, with D84.81 assigned as a secondary code.
• ✓Include evidence of immune impairment (recurrent infections, low immunoglobulin levels, abnormal lymphocyte counts) and the causal link between the underlying condition and the immunodeficiency.

Commonly Confused Codes